Investigation suggested the issue was with the initial Hyper-V configuration as removing the virtual NIC from the guest allowed it to boot without issue. Re-adding the same virtual NIC reproduced the problem, but adding a new virtual NIC (on a different physical socket in the host) brought back full functionality. Note that as far as the OS is concerned this is a whole new NIC, so you’ll need to manually reconfigure TCP/IP addresses if it was on static entered address before.
Connect to admin shares on non-domain joined system
Needing to add a non-domain joined Hyper-V host to a Veeam B&R server gave the usual issues with credentials,...