This can happen because of time out setting on server or sometime due to firewall. To resolve this issue you will have to set a keep alive time for the session.
After you set a keep alive time putty will send a packet after the specified seconds to keep the session live.
Generally you can set it to 240 seconds i.e. 4 minutes. But at times you may have to keep it low. Like when I connect from my home laptop to my AWS EC2 instance I’ve to keep it at 2 secs.
To set it:
- Open Putty.
- Load the session for which you are facing timeout issue.
- Click on Connection in the left pane .
- Finally click on “Session” in left pane and save the session.