Hyper-V VMCONNECT.EXE stopped working after new install of Docker Desktop for Windows v4.0.0.0

Docker Desktop
1

My Hyper-V host is an Intel i7 machine with Windows 10 v2004, fully updated. I installed Docker Desktop for Windows newest version just yesterday, think it was v4.0.0.0. I have never used Docker before. After reboot I cannot connect to Hyper-V virtual machines with Vmconnect.exe (the “Connect” choice in Hyper-V manager) anymore.

Click Connect in Hyper-V manager, the vmconnect window opens with status “Connecting to ‘vmname’…”, after 1-2 minutes it times out with “Cannot connect to the virtual machine. Try t connect again. If the problem persists, contact your system administrator. Would you like to try connecting again?”

I can still connect with RDP but it cannot be used if the guest vm does not have networking, in that case Vmconnect is the only way to connect to a Hyper-V vm. So the issue is quite serious, I have “lost” one VM already not being able to connect to it at all.

I have googled everything I can. Tried changing port from 2179 to 21791, and back. Tried other registry settings, and back when they didn’t help.

Wireshark does not show any traffic from the vm host, 192.168.100.100, to any guest vm port 2179 (or 21791 when trying with that) in the same /24, when trying to connect with Vmconnect. Wireshark capture filter: port 2179 (or 21791).

Only port 2179 captured packets are something that look like self connects within the various Hyper-V virtual adapters in 172.16.0.0/12 range. I’m not a network pro so no idea what this means. The route table looks sane, default route 0.0.0.0/0 metric 11, 192.168.100.0/24 metric 21, everything else has a higher metric. The interface is correct.

Hyper-V virtual switch has no problem, VM’s are able to connect to internet when being RDP’d to. It is not the default switch but a created one, external network, allow mgmt os.

I have now uninstalled Docker Desktop for Windows and rebooted several times, but the problem persists. And no I don’t have backups up to the moment of installing Docker. My bad. But this really is not what one would expect to happen.

2

Even stranger, ssh doesn’t work from cmd/ps1 shell anymore:
ssh: connect to host 192.168.100.200 port 22: Unknown error
ssh used: C:\Windows\System32\OpenSSH\ssh.exe

But using ssh from Cygwin does work without any issues.
ssh used: /usr/bin/ssh on an updated Cygwin-x64
Cannot be a firewall issue because I’ve disabled it.

Ssh works from any guest vm, only the host is affected. Seems to point that everything is a host only issue, where Docker Desktop was installed. What did the Docker setup do to my computer, and why was that not undone with uninstall?!?

3

Whole Windows networking doesn’t work: I can ping any host in the LAN (vm or physical), but I cannot browse to it with Explorer like \\192.168.100.220 .
Network troubleshooter/Diagnose cannot find anything.

Shell is not any better:
net use B: \\192.168.100.220\Shares /user:testuser
( over half a minute wait here; also tried: net use * )
System error 67 has occurred.
The network name cannot be found.

I did absolutely no other changes to the system except install Docker Desktop. It’s a fairly minimal install due to its role as a Hyper-V host. Worked well for years and now this.

Using network reset is the dead last option to try because it will probably delete Hyper-V virtual switches and in worst case I will have to reconfigure them for 100+ vm’s. What does the Docker Desktop install do to cause this.

4

Spent 3 hours doing a reinstall of WIndows 10 v2004 keeping data and settings. There’s no change. Vmconnect doesn’t work, SMB connections don’t work outwards, SMB connections do work inwards to the host, ssh out doesn’t work.

Server and Workstation services are running. Hyper-V vm’s do work normally when RDP’d to; can access internet, can access SMB shares on the host.

Utterly out of ideas at this point. What’s left is to reset networking with probably catastropic consequences to Hyper-V virtual switches, and ultimately reinstalling Windows from scratch (and never touching Docker again).

5

Networking reset (winsock and ip) did not help, no change regarding this issue. Self-connect SMB to server’s own ip ( \192.168.100.220 ) doesn’t work, self-connect SMB to server’s name ( \SERVER ) appears to work but access to shared folders doesn’t work, SMB out doesn’t work, VMConnect doesn’t work.
But accessing SMB shares on the server from outside works.