Collaborative editing / Synchrony fails only for some users

[DevOps Technical User]

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.

[Sattesh M]

Hello Dr. Markus,

It is interesting that this is the only user who is experiencing the issue.
As you've mentioned that for most part, the issue does not occur when the user uses another PC, or VM, there might indeed be something wrong with the PC, or the browser that is causing the issue.

First, to see if the issue is with the browser or PC, can we know if the user is able to publish their changes when using other browsers in the PC, instead of Chrome?

If the issue is only on Chrome, on the user's PC, then first, check to see if they have any Extensions enabled in Chrome.
If they do, try disabling all of it, and opening Confluence in an incognito session, and see if they hit into the issue still.

Do let me know if you have any question.

Cheers,
Sattesh

[DevOps Technical User]

Hi Sattesh, 

user tested all momentarily thinkable combinations of incognito, non-incognito, Chrome, Explorer. Issue remains. 

Is there any way of increasing debug log for Synchrony sessions?