That is very strange, but sadly not unexpected. There has been a lot of noise lately, with the websocket draft changes in new browser versions.
Would you mind sending me a dump of whatever error messages the chrome console shows? If there are none, could you perhaps send a screenshot of the last page of connections from the chrome network tab? I'd be wickedly grateful!
The db should probably be split across more mongodb instances, as it quickly grows wickedly huge - but granted a bit of patience, it does work.