Some users also receive error messages such as “Disconnected from World of Warcraft” or “Disconnected with error BLZ51900075”, which means the same thing, that the user has been disconnected from the server.
This is not the only explanation for this bug, as many users have complained that the bug occurs even with a normal internet connection. Blizzard’s support claims that this bug was not too active before the release of WoW Legion.