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by anonymous
Hi guys,

I'm configuring for the first time a RUT951.

It's connected to the internet by Mobile SIM in NAT mode, so it's natting the LAN hosts on the mobile connection.

By the way just configuring the router in this fashion was hell  :D

Un fortunately I still have issues with the port forwarding; The goal is to forward some ports (like 443 or 4443) from the external dynamic ip address to this specific internal host.

Apparently I tried every possible setting under Firewall section but it simply does not work.

Is there a technical limit on port forwarding on connections with dhcp ip address like mobile?

Thank you for your help.

by anonymous


Could you login to router's WebUi, navigate to Network -> Interfaces, and check, what IP is associated to [mob1s1a1] interface?

Best regards,

by anonymous

Hello! I'm happy to help.

There shouldn't be any technical limit on port forwarding for connections with dynamic IP addresses such as mobile. However, there are some things to consider when setting up port forwarding on a router.

Firstly, make sure that the external port that you are forwarding is not being used by any other services on your network. Otherwise, there may be conflicts which prevent the forwarding from working properly.

Secondly, check that the internal IP address of the host you are forwarding the ports to is correct. If it has changed since you set up the port forwarding rule, it will need to be updated.

3 Answers

0 votes
by anonymous

are you sure you have a routable IP address on your WAN side?

Most mobile providers that give you dynamic ip addresses actually
NAT you to another public IP in order not to waste the rare IPv4
addresses. Therefore you share "your" public IP with oher users
and there is no way to connect to your router from the internet.

My solution is to get a static public IP address from my mobile provider
which costs me around 15 EUROs per month (ISP is Magenta Austria).


0 votes
by anonymous
The mob interface has a private ip address, like 10.57.x.x...

Guess it's a double NAT then, so the ISP is natting me and of course I NAT my internal devices a second time.

Just to be sure.. that's the firts time I work with a SIM so I wonder if it's the common approach or if it's possible to see a public ip (with the ISP correct settings) using a SIM or not.

Thank you!
0 votes
by anonymous
Assuming, you want to have access from the public internet to port 443 of your RUT (running own web server there ?), you can achieve this using a VPN (wireguard recommended) via intermediate server, having fixed public IP. This can be a very cheap, small VPS. I have one for 2.5E/month.

Usually, it is a good idea simply to ask for a solution for a problem, without "forcing" a specific method.