I was thinking about this post from yesterday.

If the only character you can play is the super low level one (which is in free range) could it be that there is an issue with your subscription period? (Maybe not on your side but on theirs)

Edit: ah sorry did not see the additional comments that its an ISP issue.

I know it can cost money, but then I really suggest to use a VPN. I do use VPN cause it fixes some connectivity issues. I still get disconnected during some strange events like the air force one in the saucer but otherwise it works.