Hello o/
This is a 9 month old problem that Blizzard has not addressed or even acknowledged. Players have narrowed it down to an AMD gpu problem for the 6000 series and older…
and it comes through as a “disconnect” error on Blizzard’s end, but it is not a disconnect because nothing else disconnects, including bnet. Problem seems to have originated from the Vessel of Hatred expansion, and being a persistent online world, even if you don’t own VoH it is still a part of the game.
There’s 369 posts here from August 2024 up to today, with the largest surges occurring every new season. Some people have managed to reduce the problem but only to about once every 10-15 minutes if you want to scroll through and try their ideas. Of course being angry at Blizzard and not playing is understandable too.
Good luck! o7