This is the same unsolved issue I have trying to install Kali. I assume that your recreating the network settings from the qubes settings in the pure setting? It sounds like it. You can also try 255.255.255.0 as subnet rather than 255.255.255.255.
I have also had your problem with ubuntu where I couldn’t get it to detect the wifi or network.
I have found it notoriously difficult to get info about this stuff. People come forward and tell you they have done what you’re trying to do but then disappear when you can’t recreate what they supposedly did. Such is the Linux world though I’ve found time and again.
Good luck. Keep us informed.