Quectel RM520QAE not receiving data sent from UPF



I am using Open5GS as core network and Quectel modem connected to a Raspberry Pi 4 as UE.

I have an edge Raspberry Pi 5 with a docker container that has the edge UPF service inside. This UPF service has an interface called ogstun:

inet netmask destination
unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 500 (UNSPEC)
RX packets 303555 bytes 150399928 (150.3 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 220176 bytes 40154639 (40.1 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

This interface communicates with the modem, which has the ip (changes with each connection).

When I send information from the UPF interface to the modem, the modem seems to not receive the information because I do tcpdums on the LAN interface inside the UE Raspberry Pi, and it does not receive anything. The ports opened by the modem seem to be the following, using nmap from the console on the upf container:

root@f950008576d4:/open5gs# nmap -p 1-65535
Starting Nmap 7.80 ( https://nmap.org ) at 2024-04-30 16:42 CEST
Nmap scan report for
Host is up (0.073s latency).
Not shown: 65532 closed ports
80/tcp   filtered http
443/tcp  filtered https
1555/tcp open     livelan

Nmap done: 1 IP address (1 host up) scanned in 18.97 seconds

I do not know what is happening exactly, but I think that the problem is the data sent is blocked because the ports are not opened externally. How can I do port forwarding on the modem? How can I open ports on the modem?

Dear @neruzz
What did you want to test? Which ports do you want to open?

I just want to know how to open ports (any port). I want to know how to open them TCP or UDP or both. How to set them open or filtered. And finally I would want to know what is the port 1555 livelan shown in the nmap command and why it is also not accepting data from outside (sending data to 1555 is also not arriving ro the device connected to the modem).

Also, if I am connecting the modem using USB how can I send the data received by the modem on the opened port to the device which the modem is connected to?