Can you try to test these ? :

 

A. try to send a message every a few seconds.

 

B. join the chat in one browser , and after 2 minutes , join the chat using another browser .

 

If all conversations disconnected in same time , I think the ASP.NET is reseted by an unknown reason .

 

I will help to find the reason after you get a conclusion .

 

Regards , Terry .