I see there are continuous attempts to login into my computer via ssh using usernames, like joan florin root from 60.169.22.118,

-how can I forbid ssh access and only allow it to users with specific key.

-or for now how can I block traffic from that specific ip.

-or any other ways of securing more the connection to my home network.

I do have vpn, but the problem is, the service goes down every now and then, so ssh is the only sure, or constant service that can tell me when my server is up and running at home.