The issue is I can ping out from the server but cannot ping into the server.
This is a Rocky Linux 8. Not the stream version. The firewall is bastille-firewall.
The bastille-firewall has port 80 and 443 open and they are working great.
When I shutdown bastille-firewall, everything works great. Can ping out and ping in using zerotier ip addresses.
When I run bastille-firewall, can only ping out. Cannot ping in. 
I am assuming the problem is at the bastille-firewall.
Does anyone know what setting has to be set on bastille-firewall so that zerotier will work?
I am using bastille-firewall because it comes with ispconfig control panel. Something like cpanel but open-source.
Hope to receive some advice on how to solve this issue.