Hyper-V Suddenly Stopped Connecting to VMs

For no reason I can see, none of my Hyper-V virtual machines will start. This morning they did, now they don't. It looks like a Windows Defender update may have happened in the meantime but disabling the firewall didn't help. I have 4 virtual machines, 3 windows 10, one windows 11. None of them will start with "cannot connect to the virtual machine. try to connect again..."

Another thing that happened as of yesterday is that I'm getting a notice that there are two devices with the same IP on my home network. Not sure if there's a connection to the Hyper-V thing but I don't know how to fix that either.