Hey @JPMcWhiskers! Make sure to put this on the bugreport forum as well!
It sounds like an IT issue, since it’s having an issue with the IP address. Try setting an exclusion in your firewall, or maybe going into your network settings and allowing access for the program before starting it? Strange though, it shouldn’t NEED internet.
Sorry I couldn’t help more, but you might find more help on the bugreport forum. As 5.1 isn’t technically released yet we need all the feedback we can get to make sure 5.1 is as stable as possible on release!