How to unblock an IP from Fail2ban
By default, Fail2ban only blocks IPs that attempt to log in with an incorrect password via SSH 5 times within 10 minutes.
To check if any IPs are blocked, run:
sudo fail2ban-client status sshd
To unblock a specific IP that was blocked for failed SSH login attempts, run the following command (where x.x.x.x is the IP that is being unblocked):
sudo fail2ban-client set sshd unbanip x.x.x.x