It works, except for when it breaks. Which happens every 1-2 months. Group messages fail to send or don't show up, notifications either don't happen or unread

It works, except for when it breaks. Which happens every 1-2 months. Group messages fail to send or don't show up, notifications either don't happen or unread messages get stuck, calls seem to fail to connect at random. Last time - I think it was just a pair of weeks ago (I'm bad with remembering exact times), even the web version haven't worked (usually, it still does).