"Signing in" forever

I can no longer get past the “signing in (account name)” screen. Since I have not changed any settings anywhere (steam, computer, etc.) I don’t know what I am supposed to do. Searches for similar problems have not turned up anything so far. Since I am not in the least interested in matchmaking and hate the idea that I have to be connected at all, I am particularly sad that some multiplayer issue seems to be hindering my ability to start the game.
Any tips for a steam client user and tech-incompetent?

In this section there are several threads related to this. First thing to do would be to sign in to shift.gearboxsoftware.com and make sure the name and display name fields are filled out.

If after a restart that doesn’t solve the sign-in issue, it could be a firewall issue. This could be the software firewall on your PC (probably Windows Defender) or the built-in firewall on your modem/router that provides your internet connection.

You should be able to find instructions for opening up Windows Defender to alluw BL3 full access. If that doesn’t fix it, you’ll need to check that your modem/router is allowing the needed connections through. That’s going to be hardware/supplier dependent though.