The server seems to be chosen at character creation and/or world selection.

My main on Midgardsormr connects at 199.91.189.26 which gives me problems. Created a new character on Exodus. This one is located at 199.91.189.38. Just logged off after playing for an hour straight.

So if you can't wait to play you might try making a new one until you get a "good" server. Also this goes to show it is SE and not the ISP, at least in my case.