How to prolong PuTTY session:
We can provide 33 (for example) for “Seconds between keepalives” under the “Connection” option.
For AWS-EC2 and AWS-Lightsail, we have to get .pem files from the AWS console.
By using PuTTYgen, we need to create a .ppk file from the .pem file.
In PuTTYgen, Load .pem file, Save private key (can ignore warning without passphrase)
In PuTTY , Under SSH->Auth, we can load .ppk file by Browse button and connect to instance.
With the right .ppk file, it will connect to the AWS instance..