If you're a chat regular you know that things with chat haven't been so stable. We're sorry about sucking so hard at building a chat server that works. After last Friday's meltdown we took a long and deep look at the chat cluster and identified many of the problems. The TL/DR version of that is that support for Internet Exploder versions < 11, other fringe browsers and mobile browsers was causing a whole lot of server thrashing and making things hard for everyone else. If you want a more technical reason its that these old browsers either don't support websockets or would prefer not to and fall back to XHR Polling which adds a whole lot of work for the servers.
Because of this, for the time being we are reluctantly dropping support for browsers other than Chrome, Safari, Firefox and IE11. We are also dropping support for mobile devices. Our load testing and this mornings livestream show that doing so makes a huge impact for the better on performance.
We will run some tests this week with alternatives for IE < 11 and mobile. If in those tests we find solutions we'll apply them and bring back support but in the meantime, please upgrade your browser if you can.