Strange problem. I suddenly can't play online on one of my characters.

I'm replaying this amazing game yet again with my friend and it's been so much fun (: But suddenly I'm not able to be summoned or summon people or even invade.. I can see the signs of my friend and other people and it even tells me I am being summoned, but when I enter their game, it immediately disconnects back to my own world.. Same thing happen when I try to invade 🙁

This only happens on one of my characters.. I have 4 in total and the 3 others works just fine.. My best guess is that the character that can't play online on have gotten banned? But is that even possible? I've never used any kind of cheats.. I guess my character is just broken 😭

Anyway, I hope I can get some help here (:

Thanks in advance ^{^}