How to protect VPN server from hacking?

Question

Network administration

I rented a server not so long ago and launched the site, installed fail2ban and configured configurations
[DEFAULT]
bantime = 3600
findtime = 1800
maxretry = 1
# SSH jail
[sshd]
enabled = true
maxretry = 1
bantime = 108000
findtime = 36000
# ddos ​​SSH jail
[sshd -ddos]
enabled = true
maxretry = 1
bantime = 108000
But hacking attempts did not decrease from this.
What else can be added to the fail2ban configurations and what else can you recommend for protection?

Answer 1

From the minimal gentleman's set:
Change port 22
in sshd_config check the lines (make changes if necessary)
Properly configure iptables
And so on ...