Sorry, I have read many suggestions about configuring ports in this forum but none have solved my problem.
Tixati works fine - much better than Transmission which I used before.
If I stop DHT then re-start it, it goes through "Connexion" to "Online". But after a few minutes it says it is online but the port is blocked. It lists 329 nodes (this number varies).
My system:  Windows 11, Ethernet with a 4G modem/router. No ISP account (uses SFR). Mullvad VPN.
I specifically authorised Tixati in the firewall (Windows Defender) and opened the TCP and UDP ports, in and out (for good mesure):
4001, 6881-6889, 6969. Tixati says it is using 22208 so I added that too.
The modem shows UPnP for Tixati ext. 22208 - int. 22208 for TCP and UDP  (set by itself).
What else do I need to do to unblock this port?  Which port?
(Does it really matter that DHT says the port is blocked? - it has a lot of nodes and everything works fine.)

What you are facing is not a blocked port but a bug, as far as I have experienced. Use a port mapper app to forward that port(22208) and then start Tixati. Tixati has a somewhat broken port forward that works if you have a public IP, but doesn't work in a shared IP or vpn. I am facing the same problem, and you can take a look at my post: https://forum.tixati.com/support/8710

I have solved the issue using a portmapper, but a Fix from the Tixati side would help very much. Help us KH.