Not sure if this been covered but if you get stuck in the doors while it opens it will give invalid position and disconnect you, also some times doors will stay up somehow letting you enter and afterwards doors open up slightly making it impossible to exit without teleporting. Didnt manage to get a video about the door staying up
#Alien doors
queen moat
icy knoll
not only with doors but if you double click the enter dungeon button you also will get the "Invalid position" thing, happened to me several times