Big issue with multi net adapter cards

Question

Since some weeks I encountered a strange behavior.

A restart changes guid, if index and description of a physical network adapter (on multi net adapter cards PCIe cards)

System details:

Windows 11 Enterprise 24H2 (tested with patch level 2025-10 and 2025-11)

Autopilot hybrid joined machines.

driver independent, tested with Microsoft and vendor drivers, Realtek and Intel cards.(e.g. Realtek PCIe 2.5 GBE Family Controller or Intel(R) PRO/1000 PT Dual Port Network)

Tested with AMD and Intel mainboards (not older than 3 years).

Likelihood increases the more net adapters a PCIe card has.

E.g. with 4 net adapters 80-90% chance after a restart to change guid, if index and description.

With a 2 net adapters maybe 20% chance to change.

The big issue is, if guid, if index and description change, then the VMSwitch configuration fails and resets the VMSwitch to private, killing all connectivity. Basically making any VM useless!!!!!

If I look at the MAC address, then after a restart, it can have the guid, description, if index and even VMSwitch which was before on a different MAC or it has a new guid etc... and has no VMSwitch assigned.

Answer 1

Hello Gerhard,

This is a known regression in Windows 11 Enterprise 24H2 (patch levels 2025-10 and 2025-11) affecting systems with multi-port PCIe NICs. The restart causes network adapter GUIDs, interface indexes, and descriptions to be reassigned unpredictably, which breaks Hyper-V VMSwitch bindings. The current guidance is to use MAC address, based binding or PowerShell scripts to reapply VMSwitch configuration after reboot until a permanent fix is released

Harry.

Answer 2

It seems that you are experiencing issues with GUID changes for network adapters on multi-adapter PCIe cards after restarts, which is affecting your VMSwitch configuration. This behavior can lead to connectivity issues with your VMs, as the VMSwitch may reset to private when the GUID, index, and description of the network adapters change.

While the specific cause of this behavior is not detailed in the provided context, it is known that changes in network adapter settings can occur due to various factors, including driver updates or system configurations. Here are some general troubleshooting steps you might consider:

1. Check Driver Compatibility: Ensure that you are using the latest drivers from the manufacturers for your network adapters. Sometimes, using generic drivers can lead to unexpected behavior.
2. Registry Settings: Investigate if there are any registry settings that might be influencing the behavior of network adapters. In some cases, specific configurations can help stabilize the GUID assignments.
3. Network Adapter Settings: Review the settings for the network adapters in Device Manager. Ensure that there are no conflicting settings that might cause the adapters to behave unpredictably.
4. Windows Updates: Make sure that your system is fully updated. Sometimes, Microsoft releases patches that address specific hardware compatibility issues.
5. Virtual Switch Configuration: After a restart, if the VMSwitch configuration fails, you may need to reassign the VMSwitch to the correct network adapter manually. Consider scripting this process to automate the reconfiguration if it happens frequently.
6. Contact Support: If the problem persists, consider reaching out to Microsoft support or the hardware vendor for further assistance, as they may have more specific insights into this issue.

This situation can be quite complex, especially with multiple adapters involved, and may require a combination of approaches to resolve effectively.