diff --git a/CLAUDE.md b/CLAUDE.md
index a78f253..5a1aed0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -106,10 +106,13 @@ instead of working around it.
    All host identity derives from the TPM at runtime (signing key at persistent
    handle `0x81000100` — a **non-reserved owner handle**, deliberately NOT the
    EK slot `0x81010001` nor the SRK `0x81000001`, which firmware/swtpm
-   provisioning already occupy; cert at NV index `0x01800001`, hostnqn derived
-   from the cert serial). If a change needs per-host data, it belongs in the
-   enrolment flow, not the image. (The handle is overridable via
-   `rd.dot1x.handle=` / `fleet-enrol -handle`.)
+   provisioning already occupy; cert at NV index `0x01800100` — also chosen to
+   avoid **OEM platform NV**: a Dell 820 firmware squats `0x01800001`–`0x01800004`
+   + `0x01810000` as `platformcreate|policydelete` indices that no owner/BIOS
+   clear can remove, so the original `0x01800001` collided; hostnqn derived from
+   the cert serial). If a change needs per-host data, it belongs in the enrolment
+   flow, not the image. (Both are overridable: `rd.dot1x.handle=` /
+   `rd.dot1x.nvindex=` / `fleet-enrol -handle -nvindex`.)
 1. **The hook ordering in `dot1x-macsec-up.sh` is load-bearing.**
    NV-cert extraction → supplicant start → wait for `Authorized` + macsec0 →
    DHCP **on macsec0** → hostnqn derivation. Never DHCP before auth
diff --git a/README.md b/README.md
index 612c960..6dfa41f 100644
--- a/README.md
+++ b/README.md
@@ -111,7 +111,7 @@ release only changes which artifact image feeds them:
 
 ```
 rd.neednet=1 systemd.volatile=overlay \
-rd.dot1x.nvindex=0x01800001 rd.dot1x.timeout=60 \
+rd.dot1x.nvindex=0x01800100 rd.dot1x.timeout=60 \
 rd.nvmf.discover=tcp,NVMET_TRADDR,4420 \
 root=/dev/mapper/root rootfstype=erofs rootflags=ro \
 systemd.verity=yes roothash=<from verity.json> \
diff --git a/docs/TODO.md b/docs/TODO.md
index 3ab4651..a0c251d 100644
--- a/docs/TODO.md
+++ b/docs/TODO.md
@@ -783,7 +783,7 @@ smoke test.
     returns MSK); a `hostapd` wired authenticator does 802.1X + MACsec on an
     **isolated bridge per workstation** (flat VLAN can't auth — EAPOL dropped +
     MACsec is P2P). `enrol/tpm-provision.sh` creates the key in the TPM at
-    `0x81000100` + writes the cert to NV `0x01800001`. Starting solution **signs a
+    `0x81000100` + writes the cert to NV `0x01800100`. Starting solution **signs a
     CSR** (key stays in TPM); **TPM attestation** (ACME `device-attest-01`) is the
     documented upgrade on the same CA. **BENCH-VERIFY** items flagged in the files:
     hostapd MACsec build, openssl tpm2 provider vs pkcs11 key ref, EAP-TLS version.
@@ -1026,7 +1026,7 @@ path needs **no tpm2-tools key-gen / no openssl tpm2 provider / no curl** in the
 image (removes the biggest bench risk — the provider `handle:` key-ref). It
 ensures the ECDSA key at `0x81000100`, builds the CSR, POSTs CSR+context to
 `rd.fleet.enrol_url`, shows the broker fingerprint on Plymouth, polls `/status`,
-and writes the leaf cert to NV `0x01800001`. The dracut hook `tpm-enrol.sh`
+and writes the leaf cert to NV `0x01800100`. The dracut hook `tpm-enrol.sh`
 (initqueue/settled prio 25) is now a thin GATE: empty-NV check (`tpm2_nvread`,
 still needed for the secure-path read) → pre-auth DHCP on `en*` (nmcli override of
 the secure-mode unmanaged drop-in) → `exec /usr/sbin/fleet-enrol` → reboot to
@@ -1071,7 +1071,7 @@ have their EK there), so enrolment could never create our key.
     **`0x81000100`** (non-reserved owner handle; threaded through `fleet-enrol
     -handle` default, `rd.dot1x.handle=` cmdline knob baked by `extract-artifacts.sh`,
     `wpa_supplicant-dot1x.conf`, the bench scripts, invariant #1, and the design docs).
-    NV `0x01800001` (owner range) is unchanged.
+    NV index was `0x01800001` here (owner range); it MOVED to `0x01800100` in a later finding (OEM platform-NV collision on the 820 — see below).
   - **EnsureKey hardening:** (i) evicts a genuine *stale signing key* at the handle
     and recreates (self-heal for old provisioning leftovers); (ii) **refuses to evict
     any restricted-decrypt object (EK/SRK)** as a safety net — never clobber the TPM's
@@ -1096,7 +1096,7 @@ have their EK there), so enrolment could never create our key.
 
 **FOLLOW-UP HARDENING:**
 - **Content-aware NV presence check — BUILT 2026-07-03.** `fleet-enrol -check-only`
-  (no network / no key-gen) reads NV `0x01800001` via `tpmkey.ReadNVCert`, parses it as
+  (no network / no key-gen) reads NV `0x01800100` via `tpmkey.ReadNVCert`, parses it as
   X.509, checks the validity window, and — when a real fleet CA is bundled (`-cacert`,
   default `radius-ca.pem`) — verifies it **chains** to it. Only a valid fleet cert counts
   as enrolled (rc 0); empty/garbage/foreign/expired → rc 20 (enrol + overwrite;
@@ -1109,10 +1109,30 @@ have their EK there), so enrolment could never create our key.
   Tests: `classifyNVCert` unit table (valid/expired/garbage/foreign/no-CA) + `simtest`
   ReadNVCert roundtrip across the 512B chunk. **BENCH-VERIFY** on a real boot: a garbage/
   foreign NV now enrols instead of "normal boot".
-- **De-enrol / TPM-reset procedure** for re-testing: `tpm2_nvundefine 0x01800001 -C o`
+- **De-enrol / TPM-reset procedure** for re-testing: `tpm2_nvundefine 0x01800100 -C o`
   (+ `tpm2_evictcontrol -C o -c 0x81000100` for a stale *app* key — never the EK), or
   BIOS "Clear TPM". Document in the bench README.
 
+**BENCH FINDING 2026-07-03 (FIXED) — NV index `0x01800001` collided with OEM
+platform NV; moved to `0x01800100`.** The Dell 820 kept "finding a cert" and
+bypassing enrolment even after repeated BIOS TPM clears. `tpm2_nvreadpublic`
+showed the truth: `0x01800001` on that hardware is a **firmware/platform** index
+(`platformcreate|policydelete|writelocked`, 70 bytes — NOT our cert; siblings at
+`0x01800003/4` + `0x01810000` share it), which **no owner/BIOS clear can remove**
+(`TPM2_Clear` spares `platformcreate`; `policydelete` needs the platform's secret
+policy). So our chosen index was permanently occupied by Dell — the blind check
+false-positived on it, and even the content-aware check would have failed at the
+NV **write** (can't undefine a platform index). Same class as the EK-handle
+collision. Fix: **moved the NV cert index default `0x01800001` → `0x01800100`**
+(free on the 820; owner range; overridable via `rd.dot1x.nvindex=`), threaded
+through the cmdline (`extract-artifacts.sh`), `fleet-enrol -nvindex`, the dracut
+hooks, bench scripts, invariant #1, and docs. Also **hardened `WriteNVCert`** to
+refuse a `platformcreate` index with a clear "pick a free owner index" error
+instead of a confusing undefine failure (regression `simtest/
+TestWriteNVCertRefusesPlatformIndex`). **BENCH-VERIFY:** 820 now enrols at
+`0x01800100`; and check `tpm2_nvreadpublic` on any OTHER hardware model in the
+fleet — if a vendor also squats `0x018001xx`, pick a value free on all of them.
+
 **BENCH-VERIFY (host side, before trusting):** (a) go-tpm against a REAL TPM +
 swtpm on the target (the simulator proves the ceremony, not the device) — **the
 stale-key fix (above) is the first real-TPM result; re-boot to confirm it now
@@ -1159,7 +1179,7 @@ Verification found + fixed two things the `mock` path had hidden:
   FreeRADIUS (next, before host enrolment).
 
 How a host gets its **802.1X EAP-TLS client identity** the first time — the key at
-TPM handle `0x81000100` + cert at NV `0x01800001` that invariant #1 says must come
+TPM handle `0x81000100` + cert at NV `0x01800100` that invariant #1 says must come
 from enrolment, never the image. Distinct from #10 (that enrols *Secure Boot*
 PK/KEK/db); this enrols the *network identity*. They share the provisioning UKI +
 isolated-environment vehicle. Pairs with #8 + the CA decision (start **step-ca**,
@@ -1170,7 +1190,7 @@ on an empty TPM the host generates a key *in* the TPM, builds a CSR, submits it
 an enrolment **broker**, and shows a **fingerprint** on the Plymouth splash; an
 admin visually cross-checks that fingerprint against the broker's pending-list and
 approves; the broker has step-ca sign the CSR and returns the cert; the host writes
-it to NV `0x01800001` and proceeds to authenticate. Sound, recognised pattern
+it to NV `0x01800100` and proceeds to authenticate. Sound, recognised pattern
 (SSH/WireGuard/Signal-style OOB verification); good fit for invariant #1.
 
 **Key design decisions (settled 2026-06-22):**
diff --git a/docs/design-v2-errata.md b/docs/design-v2-errata.md
index 0cf02ae..9d6a495 100644
--- a/docs/design-v2-errata.md
+++ b/docs/design-v2-errata.md
@@ -85,7 +85,7 @@ approval** — on an empty TPM the host generates a key *in* the TPM
 (`0x81000100`), submits a CSR to an enrolment **broker** (reachable via the same
 pre-auth permit-set, e.g. an `/enrol/` location on the serving nginx → broker →
 step-ca signer), and shows a fingerprint on the Plymouth splash; an admin
-cross-checks it and approves; the signed cert is written to NV `0x01800001` and
+cross-checks it and approves; the signed cert is written to NV `0x01800100` and
 authentication proceeds. Enrol triggers on **empty-NV only** (expired cert →
 automatic renew; auth-failure-with-cert → alert, not re-enrol). The fingerprint
 authorises *which device*; **TPM attestation** (step-ca ACME `device-attest-01`)
diff --git a/docs/fleet-management-design.md b/docs/fleet-management-design.md
index 5bcbeae..63cc389 100644
--- a/docs/fleet-management-design.md
+++ b/docs/fleet-management-design.md
@@ -20,7 +20,7 @@ These are consequences of the CLAUDE.md invariants, not preferences:
    stateless and buffers only in RAM (best-effort).
 2. **Identity from the TPM, never baked.** No per-host state in any artifact
    (invariant #1). The agent derives identity at runtime from the **TPM-held
-   cert** (key `0x81000100`, cert NV `0x01800001`) — the same identity used for
+   cert** (key `0x81000100`, cert NV `0x01800100`) — the same identity used for
    802.1X EAP-TLS and the NVMe hostnqn. No enrollment token in the image.
 3. **Pull-based control, no inbound surface.** The boot LAN is locked down and
    segmented; we do not open an always-on inbound control port on hosts. Hosts
diff --git a/docs/ssp.md b/docs/ssp.md
index 999a309..fb5e584 100644
--- a/docs/ssp.md
+++ b/docs/ssp.md
@@ -91,7 +91,7 @@ manifest. One commit = one release = one digest = one manifest entry.
 3. **Initramfs (dracut)** brings up the NIC and performs **802.1X EAP-TLS**
    network authentication using a **private key held in the TPM** (persistent
    handle `0x81000100`); the client certificate is read from TPM NV index
-   `0x01800001`.
+   `0x01800100`.
 4. On authorisation, **MACsec** is established on the access link (link-layer
    encryption/integrity); the host then obtains an IP **on the MACsec interface**
    via DHCP.
diff --git a/docs/tpm-enrolment-design.md b/docs/tpm-enrolment-design.md
index 4930ab0..891c6a9 100644
--- a/docs/tpm-enrolment-design.md
+++ b/docs/tpm-enrolment-design.md
@@ -8,7 +8,7 @@ end-to-end *minus* the human-approval queue; the only unbuilt piece is the
 **enrolment broker**.
 
 How a diskless host acquires — and keeps — its **one cryptographic identity**: a
-signing key at TPM handle `0x81000100` and a cert at NV index `0x01800001`.
+signing key at TPM handle `0x81000100` and a cert at NV index `0x01800100`.
 Invariant #1 forbids baking any per-host state into the image, so this identity
 **must** be minted at enrolment, at runtime, from the TPM. That single identity is
 then reused for everything: **802.1X EAP-TLS**, the **NVMe hostnqn** (derived from
@@ -29,7 +29,7 @@ separate box — is what makes the two designs one coherent identity story.
 ## Design philosophy (forced by the architecture invariants)
 
 1. **One identity, minted once, reused everywhere.** Key `0x81000100` + cert
-   NV `0x01800001` = 802.1X identity = NVMe hostnqn (`…:host-<cert-serial>`) =
+   NV `0x01800100` = 802.1X identity = NVMe hostnqn (`…:host-<cert-serial>`) =
    mTLS client identity. There is no second secret. (Invariant #1.)
 2. **The private key never leaves the TPM.** Generated *in* the TPM; only a CSR
    and the issued cert ever cross the wire — both are public. This is why the
@@ -50,7 +50,7 @@ separate box — is what makes the two designs one coherent identity story.
 
 ## The identity lifecycle (the load-bearing state machine)
 
-Triggered by the state of NV `0x01800001` and the cert within it. The three events
+Triggered by the state of NV `0x01800100` and the cert within it. The three events
 are deliberately **split** — conflating them is a security regression:
 
 ```
@@ -76,7 +76,7 @@ are deliberately **split** — conflating them is a security regression:
 
 Key generated in the TPM, persisted at `0x81000100`; CSR built with it via the
 openssl tpm2 provider (key never leaves the TPM); issued cert written DER to NV
-`0x01800001`. At boot, `dot1x-macsec-up.sh` reads the cert from NV, wpa_supplicant
+`0x01800100`. At boot, `dot1x-macsec-up.sh` reads the cert from NV, wpa_supplicant
 signs EAP-TLS with the handle key, and the hostnqn is derived from the cert serial.
 All of this is built and bench-proven; enrolment just replaces the *manual* sign
 step with a brokered, human-gated one.
@@ -174,7 +174,7 @@ pinned for mTLS — one trust anchor across 802.1X, NVMe, and management.
                                            store cert ◀───────────────────────────────
   8. GET /enrol/status/{id} (poll) ───▶
      ◀── APPROVED + cert ────────────────
-  9. write cert DER → NV 0x01800001
+  9. write cert DER → NV 0x01800100
   10. reboot into production UKI → 802.1X EAP-TLS → mTLS mgmt
 ```
 
@@ -221,7 +221,7 @@ on the existing `disable_dot1x` / `boot_splash` cmdline toggles):
   auto-detects empty-NV and branches into enrolment in early boot. Picked because it
   needs **no separate provisioning boot path** — everything stays purely
   network-booted (no USB / no provisioning media to manage). The empty-NV gate is the
-  safety: NV-write at `0x01800001` needs TPM owner auth, so empty-NV is hard to
+  safety: NV-write at `0x01800100` needs TPM owner auth, so empty-NV is hard to
   coerce. Accepted trade-offs: production carries the enrolment + pre-auth broker code
   permanently, and there is no PCR-11 discrimination. The empty-NV branch is mutually
   exclusive with the secure path, so it does not endanger the load-bearing hook
@@ -346,7 +346,7 @@ exists. Enrolment is where it comes into being.
    trigger** as a static **Go + go-tpm** binary (`files/enrol/`, `fleet-enrol`)
    talking to `/dev/tpmrm0` directly — ensures the key at `0x81000100`, builds the
    CSR, POSTs to the broker, shows the Plymouth fingerprint, polls, writes the leaf
-   cert to NV `0x01800001`. A thin dracut GATE hook (`95dot1x-macsec/tpm-enrol.sh`,
+   cert to NV `0x01800100`. A thin dracut GATE hook (`95dot1x-macsec/tpm-enrol.sh`,
    initqueue/settled prio 25) does the empty-NV check + pre-auth DHCP on the
    physical NIC + reboot-to-converge. No tpm2-tools key-gen / openssl provider /
    curl needed in the image (go-tpm does it all). Built **out of the VM** on the CI
diff --git a/files/dracut/95dot1x-macsec/dot1x-macsec-up.sh b/files/dracut/95dot1x-macsec/dot1x-macsec-up.sh
index 3ab4416..5f55cc4 100755
--- a/files/dracut/95dot1x-macsec/dot1x-macsec-up.sh
+++ b/files/dracut/95dot1x-macsec/dot1x-macsec-up.sh
@@ -31,7 +31,7 @@ if [ -z "$NIC" ]; then
         NIC=$_name; break
     done
 fi
-NVINDEX=$(getarg rd.dot1x.nvindex=); [ -n "$NVINDEX" ] || NVINDEX=0x01800001
+NVINDEX=$(getarg rd.dot1x.nvindex=); [ -n "$NVINDEX" ] || NVINDEX=0x01800100
 TIMEOUT=$(getarg rd.dot1x.timeout=); [ -n "$TIMEOUT" ] || TIMEOUT=60
 
 info "dot1x-macsec: using interface $NIC, NV index $NVINDEX"
diff --git a/files/dracut/95dot1x-macsec/tpm-enrol.sh b/files/dracut/95dot1x-macsec/tpm-enrol.sh
index 99b67bf..10a8de9 100644
--- a/files/dracut/95dot1x-macsec/tpm-enrol.sh
+++ b/files/dracut/95dot1x-macsec/tpm-enrol.sh
@@ -2,7 +2,7 @@
 # tpm-enrol.sh — initqueue/settled hook, runs BEFORE dot1x-macsec-up.sh.
 #
 # INLINE empty-NV enrolment GATE (docs/tpm-enrolment-design.md). On a secure
-# build whose TPM NV 0x01800001 is empty, it brings up a pre-auth network on the
+# build whose TPM NV 0x01800100 is empty, it brings up a pre-auth network on the
 # physical NIC and hands off to the out-of-VM `fleet-enrol` binary (Go + go-tpm),
 # which generates the key/CSR, talks to the broker, shows the Plymouth
 # fingerprint, and writes the issued cert to NV. On success this hook REBOOTS.
@@ -37,7 +37,7 @@ TESTMODE=0
 [ "$(getarg rd.dot1x=)" = "0" ] && TESTMODE=1
 
 # --- knobs (override on the kernel cmdline) ---------------------------------
-NVINDEX=$(getarg rd.dot1x.nvindex=); [ -n "$NVINDEX" ] || NVINDEX=0x01800001
+NVINDEX=$(getarg rd.dot1x.nvindex=); [ -n "$NVINDEX" ] || NVINDEX=0x01800100
 # Persistent handle for the signing key: a NON-reserved owner handle. NOT the EK
 # slot 0x81010001 (which most firmware/swtpm provisioning already occupies) nor
 # the SRK 0x81000001 — see EnsureKey / CLAUDE.md invariant #1.
diff --git a/files/enrol/main.go b/files/enrol/main.go
index 66a609f..3bbd3f8 100644
--- a/files/enrol/main.go
+++ b/files/enrol/main.go
@@ -1,13 +1,13 @@
 // fleet-enrol — inline empty-NV first-boot TPM enrolment client.
 //
 // Invoked from the dracut hook (95dot1x-macsec/tpm-enrol.sh) ONLY when the
-// secure build boots a host whose TPM NV 0x01800001 is empty. It:
+// secure build boots a host whose TPM NV 0x01800100 is empty. It:
 //  1. ensures an ECDSA signing key exists at a non-reserved owner handle
 //     (default 0x81000100 — deliberately NOT the EK slot 0x81010001),
 //  2. builds a CSR with it (key never leaves the TPM),
 //  3. submits CSR + device context to the enrolment broker, shows the returned
 //     fingerprint on the Plymouth splash, and polls until an admin approves,
-//  4. writes the issued cert (DER) to NV 0x01800001.
+//  4. writes the issued cert (DER) to NV 0x01800100.
 //
 // The hook then reboots into the normal secure path. Everything host-specific
 // (key, cert, hostnqn) is created here at runtime — nothing is baked (invariant #1).
@@ -49,7 +49,7 @@ func main() {
 	var (
 		url       = flag.String("url", "http://boot.fleet.lab/enrol", "enrolment broker base URL")
 		tpmPath   = flag.String("tpm", "/dev/tpmrm0", "TPM device path")
-		nvHex     = flag.String("nvindex", "0x01800001", "TPM NV index for the client cert")
+		nvHex     = flag.String("nvindex", "0x01800100", "TPM NV index for the client cert")
 		handleHex = flag.String("handle", "0x81000100", "TPM persistent handle for the signing key (non-reserved owner handle; NOT the EK slot 0x81010001)")
 		cn        = flag.String("cn", "fleet-host", "CSR CommonName (generic; identity is the cert serial)")
 		iface     = flag.String("iface", "", "network interface for the device-context MAC")
diff --git a/files/enrol/simtest/tpmsim_test.go b/files/enrol/simtest/tpmsim_test.go
index 5c94fde..919f460 100644
--- a/files/enrol/simtest/tpmsim_test.go
+++ b/files/enrol/simtest/tpmsim_test.go
@@ -10,6 +10,7 @@ import (
 	"crypto/sha256"
 	"crypto/x509"
 	"crypto/x509/pkix"
+	"strings"
 	"testing"
 
 	"fleet-enrol/tpmkey"
@@ -81,7 +82,7 @@ func TestEnsureKeyAndSignCSR(t *testing.T) {
 
 func TestNVWriteAndPresence(t *testing.T) {
 	tpm := openSim(t)
-	const nv = tpm2.TPMHandle(0x01800001)
+	const nv = tpm2.TPMHandle(0x01800100)
 
 	if tpmkey.NVPresent(tpm, nv) {
 		t.Fatalf("NV should be empty on a fresh TPM")
@@ -229,3 +230,32 @@ func TestEnsureKeyRefusesToEvictProtectedKey(t *testing.T) {
 		t.Fatalf("protected object was evicted (should have been left intact): %v", err)
 	}
 }
+
+// Regression for the Dell 820 finding: our NV index collided with an OEM
+// PLATFORM-created index (platformcreate|policydelete) that no owner clear can
+// remove. WriteNVCert must REFUSE such an index with a clear error (the remedy
+// is a different rd.dot1x.nvindex), not a confusing undefine failure.
+func TestWriteNVCertRefusesPlatformIndex(t *testing.T) {
+	tpm := openSim(t)
+	const nv = tpm2.TPMHandle(0x01800100)
+
+	def := tpm2.NVDefineSpace{
+		AuthHandle: tpm2.TPMRHPlatform,
+		PublicInfo: tpm2.New2B(tpm2.TPMSNVPublic{
+			NVIndex: nv,
+			NameAlg: tpm2.TPMAlgSHA256,
+			Attributes: tpm2.TPMANV{
+				PlatformCreate: true, AuthRead: true, AuthWrite: true,
+				NoDA: true, NT: tpm2.TPMNTOrdinary,
+			},
+			DataSize: 8,
+		}),
+	}
+	if _, err := def.Execute(tpm); err != nil {
+		t.Fatalf("define platform NV: %v", err)
+	}
+	err := tpmkey.WriteNVCert(tpm, nv, make([]byte, 64))
+	if err == nil || !strings.Contains(err.Error(), "platform-created") {
+		t.Fatalf("WriteNVCert should refuse a platform-created index; got: %v", err)
+	}
+}
diff --git a/files/enrol/tpmkey/tpmkey.go b/files/enrol/tpmkey/tpmkey.go
index da30bf2..569f447 100644
--- a/files/enrol/tpmkey/tpmkey.go
+++ b/files/enrol/tpmkey/tpmkey.go
@@ -2,7 +2,7 @@
 // / no openssl tpm2 provider). Provides: ensure a persistent ECDSA signing key
 // at a non-reserved owner handle (default 0x81000100 — NOT the EK slot
 // 0x81010001, see EnsureKey), a crypto.Signer backed by it (for CSR signing),
-// and NV cert read-presence + write at 0x01800001. Talks to any transport.TPM,
+// and NV cert read-presence + write at 0x01800100. Talks to any transport.TPM,
 // so the same
 // code runs against /dev/tpmrm0 (production) and the software simulator (tests).
 //
@@ -224,6 +224,14 @@ func ReadNVCert(tpm transport.TPM, index tpm2.TPMHandle) ([]byte, error) {
 func WriteNVCert(tpm transport.TPM, index tpm2.TPMHandle, der []byte) error {
 	// Undefine a stale index first (re-enrolment / resized cert).
 	if rp, err := (tpm2.NVReadPublic{NVIndex: index}).Execute(tpm); err == nil {
+		// A PLATFORM-created index at our handle is OEM firmware NV (bench-seen on
+		// a Dell 820: 0x01800001 was platformcreate|policydelete|writelocked). We
+		// cannot undefine it with owner auth, and TPM2_Clear/BIOS won't remove it —
+		// so fail LOUDLY with guidance rather than a confusing "nv undefine" error.
+		// The remedy is a different, free owner index via rd.dot1x.nvindex.
+		if pub, e := rp.NVPublic.Contents(); e == nil && pub.Attributes.PlatformCreate {
+			return fmt.Errorf("NV index %#x is a platform-created (firmware-owned) index — cannot be written by enrolment; pick a free owner index via rd.dot1x.nvindex / -nvindex", uint32(index))
+		}
 		if _, err := (tpm2.NVUndefineSpace{
 			AuthHandle: tpm2.TPMRHOwner,
 			NVIndex:    tpm2.NamedHandle{Handle: index, Name: rp.NVName},
diff --git a/scripts/extract-artifacts.sh b/scripts/extract-artifacts.sh
index befa0b2..c781f8b 100755
--- a/scripts/extract-artifacts.sh
+++ b/scripts/extract-artifacts.sh
@@ -223,7 +223,7 @@ printf '%s' \
   "$STIG_FRAGMENT" \
   "$DOT1X_FRAGMENT" \
   "rd.neednet=1 systemd.volatile=overlay " \
-  "rd.dot1x.nvindex=0x01800001 rd.dot1x.handle=0x81000100 rd.dot1x.timeout=60 " \
+  "rd.dot1x.nvindex=0x01800100 rd.dot1x.handle=0x81000100 rd.dot1x.timeout=60 " \
   "rd.fleet.enrol_url=${ENROL_URL} " \
   "rd.nvmf.discover=tcp,${NVMET_TRADDR},4420 " \
   "root=/dev/mapper/root rootfstype=erofs rootflags=ro " \
diff --git a/serving/dot1x-bench/README.md b/serving/dot1x-bench/README.md
index 1db4c37..b28c5c5 100644
--- a/serving/dot1x-bench/README.md
+++ b/serving/dot1x-bench/README.md
@@ -84,7 +84,7 @@ qm set <vmid-A> --tpmstate0 <storage>:1,version=v2.0
 3. **Enrol each workstation's TPM** (one-shot, on a provisioning network that can
    reach step-ca) — see `enrol/tpm-provision.sh`: generates the key **in** the TPM
    at `0x81000100`, builds a CSR with it, has step-ca sign it, writes the cert to
-   NV `0x01800001`. Each host gets a unique cert → unique hostnqn.
+   NV `0x01800100`. Each host gets a unique cert → unique hostnqn.
 
 4. **Set up the authenticator** — `authenticator/setup-link.sh` (bridge + macsec
    plumbing per link) then run `hostapd authenticator/hostapd-wired-<link>.conf`.
diff --git a/serving/dot1x-bench/enrol/tpm-provision.sh b/serving/dot1x-bench/enrol/tpm-provision.sh
index 29ee814..a5a658b 100755
--- a/serving/dot1x-bench/enrol/tpm-provision.sh
+++ b/serving/dot1x-bench/enrol/tpm-provision.sh
@@ -7,7 +7,7 @@
 #      (non-reserved owner handle; NOT the EK slot 0x81010001)
 #   2. build a CSR using that TPM key (private key never leaves the TPM)
 #   3. have step-ca sign it (token-gated 'enrol' provisioner)
-#   4. write the issued cert (DER) to TPM NV index 0x01800001
+#   4. write the issued cert (DER) to TPM NV index 0x01800100
 # At boot the dracut hook reads the cert from NV and wpa_supplicant signs EAP-TLS
 # with the persistent-handle key. hostnqn is later derived from the cert serial.
 #
@@ -27,7 +27,7 @@ set -euo pipefail
 
 HOSTID=${1:?usage: tpm-provision.sh <host-id>   e.g. ws-vm-a}
 HANDLE=${HANDLE:-0x81000100}
-NVINDEX=${NVINDEX:-0x01800001}
+NVINDEX=${NVINDEX:-0x01800100}
 export TPM2TOOLS_TCTI="${TPM2TOOLS_TCTI:-device:/dev/tpmrm0}"
 CA_DNS=${CA_DNS:-ca.fleet.lab}; CA_PORT=${CA_PORT:-8443}
 CA_URL="https://${CA_DNS}:${CA_PORT}"
diff --git a/serving/dot1x-bench/enrol/tpm-selftest.sh b/serving/dot1x-bench/enrol/tpm-selftest.sh
index f63d5bb..9463a9b 100755
--- a/serving/dot1x-bench/enrol/tpm-selftest.sh
+++ b/serving/dot1x-bench/enrol/tpm-selftest.sh
@@ -4,7 +4,7 @@
 #
 # Run as root on a booted workstation (the open-port test image is fine — it
 # ships the same tooling). Uses SCRATCH handle/NV and cleans them up, so it never
-# touches the real 0x81000100 / 0x01800001. Pass --use-real-handles to exercise
+# touches the real 0x81000100 / 0x01800100. Pass --use-real-handles to exercise
 # the actual locations instead (still cleaned up unless --keep).
 #
 # It validates, in order:
@@ -24,7 +24,7 @@ for a in "$@"; do case "$a" in
 esac; done
 
 export TPM2TOOLS_TCTI="${TPM2TOOLS_TCTI:-device:/dev/tpmrm0}"
-if [ "$USE_REAL" = 1 ]; then HANDLE=0x81000100; NV=0x01800001
+if [ "$USE_REAL" = 1 ]; then HANDLE=0x81000100; NV=0x01800100
 else HANDLE=0x81008000; NV=0x01500000; fi
 
 WORK=$(mktemp -d); PASS=0; FAIL=0; SKIP=0