Can the computer (the one having the issue connecting with the browser) connect to IP at all? traceroute?
Is the computer connected to a VPN?
I didnt check that, I dont wanna give you a misleading answer.
You and DH are really close.
I'll give a little of a hint, One of the times I had this issue, I was using a Dlink NAS, so I called Dlink and they were able to connect