Seeing there are no pertinent answers I can only concur a similar problem with Firefox. It entails.. err.. a game site called Animal Jam. Sometimes the servers do genuinely fail or are overloaded and the game stops. On wifi, connection fails and that's it. On LAN it's still available?
It's a Firefox failing I think, so agree. Until Firefox updates again I'm using Pale Moon, from Major Geeks and author's site.
It's a retro Firefox browser and works faster and better than Ff at the moment.
Not a solution but a work around for now.