Technical Can't log in without vpn

i have been playing on warmane for quite some time now and this last week i couldn't log in to my account and it said "Could not log in world of warcraft at this time. please try again later " but time to time it would log in normally but most of the time it said that, i tried everything from reinstalling wow to reinstalling windows and none of them worked, today i tried using VPN and it worked, i can log in normally when i change IP but it lags a lot and i don't want to use that kind of solution, not to mention pay money for vpn so i was wondering what could be the problem ? i'm 100% sure i haven't been banned since i my behevior has been proper and i doubt simple vpn can help with anything if i have been banned. can you guys help me understand what could be the problem ? since vpn worked it's probably related to my ip adress but i have been playing for quite some time like i said and never had a problem, i have not changed anything and it started this problem out of nowhere.