Connection issues with characters NOT players

I am having an issue connecting with a character. My brother and I leveled together up to 67 and just today nothing. It says I can’t load my character when I join him and the same the other way around. However, I can log into a game with him if I use my lvl 51 character and he can do the same with his level 18 character. The issue only arises when both level 67s try to get into a game together.

Any help would be appriciated