Running on 6.5.2 and behind a Nginx reverse proxy. For almost all of roundabout 300 users editing and collaborative editing works flawlessly.
So to my best knowledge and guess, config should be ok.
There is atm one user I'm aware of, who has problems while editing pages. Even when he is only editing his own previous drafts. As soon as he tries to save, saving fails, he gets disconnected from server, re-connects instantly and 2 avatars are shown. But still his changes are not published.
He sent me his changes as plain text and I (as expected) could edit and publish. I could join whilst he was editing and I could also publish while in a collaborative session with him.
Neither Confluence log nor Nginx log show exceptions or dubious entries while the fail occurs.
If he uses another PC or VM he does most of the time, not always though, not have these aforementioned problems.
If it was a problem on his PC or Browser (Chrome 68) it should hit other users, too, as we talk about enterprise managed IT with same policies and software.
If I set collab editing to 'limited' or 'off' in admin backend, his saving fails do not happen.
ATM I do not have any further idea on how to track down the failure.
