Are you on a proxy/vpn?Did you back up your saves and reinstalled Blockland and see if an add-on could be conflicting?Did you try restarting your computer?
I currently dont have any add-ons installed at the moment, and I am not on a vpn.
Try auth_init_client(); in console before joining a server and see if that does anything.
Fixed
Did you try restarting your computer?
Are you also able to reset the router? (Unplug for 30 seconds and then plug it back)