My Hyper-V vEthernet (Default Switch) is automatically deleted and re-created every few seconds

Question

On Windows 10 Pro 1809 build 17763.805 my network connectivity bounces every 2 seconds from online to offline. I'm running Hyper-V in order to use Docker Desktop for Windows.

Checking Control Panel\Network and Internet\Network Connections I see two network interfaces:

• “Ethernet” whose status swaps between my Windows Domain name and “Enabled”
• “vEthernet (DockerNAT)” Hyper-V Virtual Ethernet Adapter #2 (status "Unidentified network")

And then a third that appears and disappears every few seconds:

• “vEthernet (Default Switch)” Hyper-V Virtual Ethernet Adapter

When the Default Switch disappears, my Ethernet adapter reports a Windows Domain connection. A few seconds later, when the Default Switch reappears, my Ethernet adapter’s status reverts to “Enabled” and I lose a Domain connection while it tries to reestablish a connection.

Digging further, I see this Windows System Event Log block cycle every minute or so (the NIC identifier changes across cycles):

NIC B99A4A01-143A-4DD6-AE3C-5D6AAA8ABF41 successfully disconnected from port .

The operation 'Delete' succeeded on nic B99A4A01-143A-4DD6-AE3C-5D6AAA8ABF41 (Friendly Name: Default Switch).

NIC C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 successfully disconnected from port C08CB7B8-9B3C-408E-8E30-5E16A3AEB444.

The operation 'Delete' succeeded on nic C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 (Friendly Name: Default Switch).

The operation 'Create' succeeded on nic C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 (Friendly Name: Default Switch).

NIC C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 (Friendly Name: Default Switch) successfully connected to port C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 (Friendly Name: Default Switch) on switch C08CB7B8-9B3C-408E-8E30-5E16A3AEB444(Friendly Name: Default Switch).

Switch C08CB7B8-9B3C-408E-8E30-5E16A3AEB444 (Friendly Name: Default Switch) successfully initialized.

I initially posted this to the Docker forums.

I'm unsure what more could assist diagnosis, so please comment and I'll be happy to add any other useful details!

Answer 1

I had this same problem for a long time over several Windows 10 builds but finally found a solution. Currently running Windows 10 build 19025.1052.

There is a service on Windows 10 called "DNS Client" or dnscache that I had disabled. Once I re enabled the service and restarted Windows then Hyper-V created the default switch and it was not removed/reinstalled.

This also fixed issue with WSL 2 install that now uses Hyper-V. WSL 2 install would fail with "The RPC server is unavailable."

To enable the DNS Client service I followed the instructions here: https://wintechlab.com/enable-disable-dns-client-service/

The service has a high level of permission and the only way I could enable was by going to the registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Dnscache

and setting Start DWORD to 2 (Automatic) instead of 4 (Disabled).

Answer 2

I just had a strikingly similar issue, which materialized right after a reboot, but as I am already updated to the latest version of Windows, the chosen solution was unavailable. Furthermore, the dnscache service was already running as mentioned in the OP's comment on Reyad's answer. Eventually, there was a duplicate WSL virtual network, so I knew something was funky.

What did end up fixing the issue for me was first running sfc /scannow, then stopping and starting the hns service (Host Network Service). Then, as I am using WSL 2, I also restarted the LxssManager service. After that, the extra WSL network magically disappeared, my connections are stable, and the Event Viewer has shown no new errors.

Answer 3

Frustratingly, for myself and my colleagues sharing this problem: the solution was to update Windows 10 to 1909 (specifically, I'm on build 18363.476).

An unsatisfactory solution but the only thing that worked after several months of trying.