From my notes:
Services > Dynamic DNS
Service: dyndns.org hostname: your-public-name
Services > OpenVPN > Generate root certificates
name=ipfire, hostname=your-public-name, dept=IT, city=Phoenix, state=AZ, country=US
DHsize=2048 … root certificate done, enable OpenVPN on RED, Start openVPN server; green.
On connection status, click add, connection type as is, click add. Enter name: pavlos
Go to Generate certificate, hostname=your-public-name, org=IT, city=Phoenix, state=AZ, Country=US, valid 730 days, pk12=your-password, click on redirect gateway then save. It generates a certificate without errors shown on the previous screen. Download zip (pavlos-TO-IPFire.zip) and test.
NOTE: Openvpn server, Advanced Options … set domain your-domain and DNS to ipfire-ip
This way, I can resolve hosts by name when I openvpn home from a coffee shop.
Adjust dept, city, state, country as necessary.