I have ssh access to two servers. About 10 days ago there were 19500 attempts to login to one of those two servers. How do you protect yourself? I have passwordless SSH (key auth), fail2ban, root login disabled and i changed port from 22 to some other. What more can be done?

Edit:
Okey, from comments i understand that exposing SSH is not the best solution.

So i have found an alternative, i have spare raspberry pi 5. Could i use RPI Connect as form of VPN?