As of today, logging into retail downloads this quick update. That update deletes your realmlist.wtf file and rebuilds your client for BNET login.
You will need to now go into your WTF folder and you will see Config.wtf go all the way to the bottom of the file and either add if not there or change it if it already has a realmlist setting to
SET realmList "logon.pservername" Be sure to include the " " too!
Save then relaunch WoW.exe