Sam wrote:

...I've tried using a legacy virtual NIC, no dice...

I got it working in Hyper-V on Windows 10 Enterprise. Finally.

Many thanks to Kari at this site: Ten Forums Tutorial

It wasn't enough to merely set the legacy NIC. It was also necessary to use the Generation 1 VM - Gen 2 apparently does not work. I had been told that downstream distros from Red Hat were capable of using Gen 2-type VMs but that apparently isn't always the case.

Gen 2 does work fine with Debian-descendants.

Still doesn't get us any closer to solving the OP's problem, though...