I don't do much data center travel but wanted to do it today and was also getting Error 2021. I have done everything suggested by Votraftur with no luck. It gets stuck at retrieving world data and then errors out.

https://i.gyazo.com/2a3357e169b699b1...3974ca32ed.png

I have however been getting this error message when it crashes to error 2021 and I relog back in.
https://i.gyazo.com/baaab9b5d1cbaeb0...8f78bd5bd0.png

I'm not sure what's going on, I have tested with multiple characters and get the same thing. The last time it worked for me was back during the cloud server testing, so I'm not sure if something from that messed with my account or what. I can log in and world travel no problem on the same data center and I can create a character on other data centers. I just can't data center travel.