For a few hours now, the heading that appears on the home page of Stack Exchange sites notifying of newly active questions has not been appearing. I have had to manually refresh in order to see new activity.
I have observed this on SF, SU and right here on mSO.
Upon hitting F12 in Chrome and looking around, it appears that the WebSockets connection to sockets.ny.stackexchange.com is failing, though Chrome doesn't tell me exactly why.
On further investigation, I also seem to not be receiving notification of reputation changes, upvote/downvote changes, new comments notifications, flags, or inbox notifications.