Error - You may be using a proxy server that prevents WebSocket connections

[ITDP]

hen we edit a page or create a page, we will receive the following errors occasionally.

We have opened firewall 9443, 8091 port. 

The case would be reproduced easily if we idle the page for certain times (eg. 10mins) and click edit or create button on Confluence page.

[Nic Brough -Adaptavist-]

The usual culprit for this one is a proxy that does not support web-sockets.

Can you confirm whether you are using a proxy or not?

If there is no proxy, then the next most likely cause is that your network is not allowing access to Synchrony. You mention your firewall having opened 8091 and 9443 - are those the ports you have configured for Confluence and Synchrony?