Fix Intune Error 0x800705B4: A timeout (ERROR_TIMEOUT). In Autopilot it is typically TPM 2.0 attestation failing during self-deploying mode, or the ESP device phase timing out.

Root causes

• The device does not have a physical TPM 2.0. Virtual machines, including Hyper-V virtual TPMs, and TPM 1.2 chips cannot use self-deploying mode.
• TPM attestation endpoints for the TPM vendor are blocked by a firewall or proxy.
• Specific TPM firmware has a known attestation problem, for example Infineon SLB9672 firmware 15.22 with an EK certificate.
• The ESP timeout is shorter than the time needed to install the required apps and policies.
• The Windows version is too old: self-deploying needs 1709 or later, and 1809 or later for hybrid join.

Step-by-step remediation

1. 1On the device run Get-Tpm and confirm TpmPresent, TpmReady and a 2.0 specification version. A virtual machine cannot use self-deploying mode.
2. 2Open the ModernDeployment-Diagnostics-Provider Autopilot log and note which phase timed out.
3. 3Allow the TPM attestation URLs for your TPM vendor through the firewall and proxy, and bypass TLS inspection for them.
4. 4Update the BIOS and TPM firmware from the OEM, particularly for the Infineon and Intel firmware TPM attestation issues.
5. 5If the timeout is during the ESP, raise "Show an error when installation takes longer than specified number of minutes" and remove non-essential blocking apps.
6. 6Delete the stale device record in Intune, reset the device and retry.