Long-lived connections over WiFi get stuck

[Yuri]

I have the problem that vnc-over-ssh connection from the laptop on WiFi 
gets stuck regularly, while the local browser on the laptop still works 
fine.

Eventually vnc-over-ssh either disconnects, or can be revived by pulling 
the WiFi card out and putting it back in.

The only difference between the browser and vnc-over-ssh is that browser 
connections are supposedly shorter, and can supposedly get reset by the 
browser when they aren't responsive, while ssh connections are 
long-lived and probably intense because vnc regularly needs to transfer 
large screen portions, and ssh doesn't reconnect when stuck.


What could be a problem with long connections getting stuck? How can 
this be troubleshooted?


Thanks,

Yuri