Nuc ! It’s Nuc! 
Intel Nuc with windows and HA installed in Virtual Box
I had a similar problem, the remote connection is working fine and after a few days sometimes even after few hours, the connection stopped working. I have home assistant running in VmWare and my host system is Win10.
I mad a few changes in VmWare and then and after disconnect and connect the network adapter (in VmWare) i was able to log in. Before I made the changes I had alwalys restart the hole system (Win10).