Port Forwarding, Hairpin and OpenVPN

Good morning everyone.
I’m new to RouterOS so I need some help.
So I have a problem to solve.
First the topology:
Mikrotek 5g AX router connected via 5g to the internet, internal lan 192.168.3.0/24.
Inside the LAN there are some servers that can be reached from the outside through port forwarding. I also solved the problem of reaching the servers from within the LAN using the NO-IP FQDN of the router’s internet port via Hairpin. The problem is that I can’t do that for OpenVPN (I need it to reach an internal telephone switchboard that has OpenVpn Server enabled). Also configuring Hairpin works only by connecting from the internet and not from the Lan.
Thanks to anyone who can help me.
Ciao!!

Solved by myself.
All configured correctly with Hairpin, the issue was in the OpenVpn client. Sigh!