Open ports problem on rmnet_mhi0

Technical Support for Routers 4G LTE, 5G NR, USB modems
1

Hello maybe I've a litte custom setup.

I'm using the LTE modem rmnet_mhi0 as wan interface to get my actual IP by Interface for ddns cause all traffic is going thought a VPN host, so dyndns would show the VPN external IP.
Now I figured out that the modem has some open ports 5060 53 an some more.

  1. How can I close them ?
  2. how can I open custom ports there?
    It seems not following the usual firewall setup Iptables rules.

Best regards =)

2

How did you "detect" them?

Mostly those ports are not open for real because cellular uses CGNAT.