How can I change the connection timeout setting in Firefox?

You can change the timeout settings by typing "about:config" in the address bar and then filtering on "timeout":

network.http.connection-timeout

After the last Firefox update we had the same session timeout issue & following setting helped to resolve it.

We can control it with network.http.response.timeout parameter.

1. Open Firefox & type in ‘about:config’ in the address bar & press Enter.
2. Click on the 'I'll be careful, I promise' button.
3. Type ‘timeout’ in the search box and network.http.response.timeout parameter will be displayed.
4. Doube click on the ‘network.http.response.timeout’ parameter & enter the time value (it is in seconds) that you dont want your session not to timeout, in the box.

While this used to be possible with network.http.connection-timeout, this ceased to be used in 2001.

http://kb.mozillazine.org/Network.http.connect.timeout