WSS - Socket Abrupt disconnection

[GirishDharmaraj]

Experts,

I am facing a very strange issue - We have many clients connecting to freeswitch via SIP WSS and the client side is using JSSIP.
Suddenly for some calls made by the agent I can see "Websocket abruptly disconnected" and freeswitch side shows no logs.

I am using FS 1.10.6 and Fusionpbx 4.4 on Debian 10.
I am unable to understand where to start troubleshooting for this issue. All for some reason the tcp connection is getting abruptly closed by the FS Server.
If anyone can throw some points where all to check, perhaps I can collect the logs and discuss with you experts here.

 

[GirishDharmaraj]

To add - I found one more thing - the issue happens when the application (Google Chrome) tries to negotiate TLS v 1.3. It is also strange that for 10 calls the negotiate v.12 and the 11th call for no apparent reason is negotiating v1.3. I am not sure though that could be a reason.