Why is my ssh suddenly disconnected and automatically connected, the frequency is very high

We have a collection of troubleshooting tips available at this Community post that provide an excellent start for determining what is causing your SSH connection to disconnect. It also may be helpful to log into your Linode via the Lish console during those times to determine whether you can log in to Lish and figure out whether your networking is down or there are other errors occurring. You can also open a support ticket during these occurrences and we'll be happy to take a look at your Linode's console for any errors that may be impacting your ability to stay connected to your server.