Apple's servers (i.e. all apple.com servers incl. iTunes and App Store) not loading every couple of days
I would be tempted to do two things to troubleshoot this:


Get a new network connection - use a VPN to connect elsewhere or move the computer to an entirely new network.
Install macOS on an external drive and when you have this problem, power off the main macOS and boot to the alternative OS to test in rapid succession if this could be some odd corruption on the os.


You’ve ruled out all the big, easy targets, so this is likely to be something that’s a real edge case or wacky one-off issue. The VM connecting to the network when the host OS cannot is just baffling to me as well.