It could be since upgrading to windows 10, hangouts will intermittently disconnect and get stuck trying to reconnect, I have to press reconnect a couple of times and then suddenly it will connect back again.
Using Chrome version 51, running AVG free but have tried disabling it and still same issue (turned web protection off).
Have turned off all addons in chrome except for Hangouts addon.
Still every hour or so it will do this for 5-10 minutes then resume. Sometimes more often, other times not as often.