How To Prevent an SSH Timeout in Putty
This support article will explain how to adjust the keepalives value in Putty to prevent SSH timeouts, which is off by default.
Open Putty and go to "Connection"
Under "Sending of null packets to keep session active - Seconds between keepalives (0 to turn off)", enter a value in the text box. [Tip: 120 seconds should suffice]
Go to "Session" and save this as "Default Settings" [Tip: you can create multiple profiles here if you would like]
Done! Now every time you begin a Putty session, these settings will be used.