I have been having this problem. Only with my legion remix character, I used felrush and i moved soo quick i clipped through the world and get dc everytime I try to log into that character (WOW51900319)
No other character has this problem. I have uninstalled mods, reinstalled the game, renamed a few files to old, used command /consolecvar_default, updated graphic drivers, enabled Max Forground FPS to my monitor, enabled Ipv6, run wow.exe and battle.net in windows compatibility in windows 7 and 8, windowed mode, used move character service and made a ticket.
When I can log in, i can see for a split second my legion remix character is just stuck falling through the world in a fixed place. I honestly don’t think their is anything i can do on my end.