Tryton desktop on Ubuntu handshake operation timed out

In Tryton desktop on Ubuntu, for a connection with SSL. After being the session open for a day, the application does not respond and I get the following error in the console:

ERROR: tryton.rpc: _ssl.c: 1106: The handshake operation timed out

To fix I have to restart the tryton server every time this happens.

What can I do to avoid having to restart the tryton server?

It seems the server is blocked on some resources. If you are using the embedded web server, you should consider running trytond from a WSGI server. The embedded server is not really for production deployment but more for development.
Also it is better to delegate the SSL to a reverse-proxy.