Can't Log in

Could not log in world of warcraft at this time. please try again later - it says that when i try to log in and sometimes, NO i do not have ban and yes realmlist is correct, sometimes i can log in and than when i logout after 5 min it might not let me log in and says above mentioned, i tried logging into different accounts and it says the same, i reinstalled windows, reinstalled wow, reinstalled wow from different site, changed IP, tried messing with router, basically i tried every advice i got and NONE of them works. PLEASE HELP or tell me when i can find much needed help

Thank you in advance