I found the old guide https://www.tixati.com/optimize/router-port-forward.html  , but I don't know how to port forward using the current version. Under Network: Incoming Ports: The TCP/UDP port for peer connections and messages is just 1 #. I also have checked on: Use NPNP / NAT-PMP to forward port on router. Random port interval: Never, Random Port Range 10000 - 50000.
So, what is the protocol, local port and port range? Any information about this matter would greatly be appreciated.

Go to Settings -> Network -> Incoming ports

Put a number like 13047 or 29486 (any number above 10000 and below 65536 should be okay) in "TCP/UDP port for peer connections and messages".

Enable the checkbox "Use UPNP/NAT-PMP to forward port on router".

Pick any random port interval you like.

Select a random port range like 10000-50000.

This works on my setup with Tixati 2.57. If it doesn't work on your setup then something else should be the problem.

If it still doesn't work then try to do manual port forwarding on your router. Go to your router admin interface and port-forward Tixati's port (the number like 13047 in ""TCP/UDP port for peer connections and messages") to your computer (you may need to know your computer's internal LAN IP address to do so, and you may need to change your DHCP settings to give a permanent internal LAN IP address to your computer). To do this you also need to disable the random port interval in Tixati (pick the option "Never").

Thanks, I'll try this out.