RUTX50 - Port forwarding in Passthrough mode WAN mobile

Hi, I am using RUTX50 only as a connection to the internet via mobile data (Vodafone SIM). I do have Unifi to completely manage my home network. My router UDM Pro has a default IP address

I setup RUTX50 as follows:

  1. Changed LAN IP address to to separate from my UDM Pro router default address.
  2. Passthrough mode in WAN mobile mob1s1a1. Bridge mode did not work (no internet access).
  3. DHCP in WAN mobile mob1s1a1 is NOT disabled (no internet access when I tried to disable DHCP).

I connected LAN1 port of RUTX50 to WAN port of UDM Pro via ethernet cable. Access to internet is working fine. However, port forwarding setup on UDM Pro stopped working. I cannot reach from internet any internal network client with properly port forwarding setup. If I change back the connection to internet to previous ISP (Vodafone cable modem), all port forwarding work 100%.

What else do I need to setup on RUTX50 to allow also port forwarding passthrough from and to UDM Pro router please?

Thank you for your help.

do you have public IP address from mobile operator? Are your APN settings are correct?
Router in passthrough mode should forward everything to your UDM without additional configuration.

Yes, it should but it does not. I do not have public IP address but it should not be an issue because for example for Synology NAS I do have DDNS access. I checked it and Synology is correctly updating external IP address if there is a change (usually after modem restart).

What do you mean by correct APN settings? Most of configuration I left with default setting except what I mentioned in original post.

This is my configuration:

Thank you for any suggestions.


When you use a Vodafone SIM and Vodafone cable modem, they give different IP addresses to your router. As you may know, DDNS needs to be set up for each IP address. Therefore, the DDNS setup needs to be reconfigured to work properly.

Also, could you please check what WAN IP address the RUTX50 provides to your UDM Pro, while in passthrough mode?

Kind regards,

In your case, Mobile SIM ISP Vodafone private IP address is the matter, because you are are not receiving public IP address on your WAN mob1s1a1 that is fully-route’able to Internet with all ports opened.
For private IP address assigned to your interface, the gateway IP is placed at Carrier side and is doing NAT according to some policies.

Most likely your ISP Vodafone for Mobile is using CGNAT (Carrier Grade NAT) which is sharing same public IP address among many different users - so from Internet site you have some range of ports usable to establish sessions TCP etc.

Communication to Internet from your inside network to outside(Internet) should work, but with port-forwarding direction from Internet to you and facing your side, will not work, because port allocated and mapping will be break.
You might test it out and see using packet capture get PCAP and use Wireshark to inspect packets.

Please turn to your ISP Vodafone to ask them about routing policies and ability to buy and acquire public IP address assigned to your SIM card, in such case Port-forwarding + Passthrough will be working the same fashion as your cable-Internet.

Kind Regards,


Thank you for reply. When I am using Vodafone cable modem, port forwarding is working 100%. WAN IP address shown in UDM Pro is and it is the same as my external IP address.

When I switch to RUTX50 modem, port forwarding stopped working completely. WAN IP address shown in UDM Pro is The same address is shown mob1s1a1 of RUTX50. However, my external IP address is and the same address is picked up automatically by Synology NAS.

I am able to reach UDM Pro using address but not with address The issue is that Synology is automatically using external IP address (same as I can see on this web

Is it possible to setup RUTX50 to have just one external IP address everywhere? The same setup as when using Vodafone cable modem.

Thank you.

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This is regarding the case @roberttz mentioned earlier, which he described quite clearly. The RUTX50 isn’t the issue here. You simply need to get a public static IP address for your mobile SIM card, just like you have for your cable modem from your ISP. This usually comes with an additional cost and isn’t included in the standard service package. You’re fortunate to have a static IP address for your cable modem without any additional charges:)

Kind regards,


I don’t have static IP address for Vodafone cable modem connection. IP address is also changing from time to time, usually after power loss / cable modem reboot. The difference is that cable modem provides the same public IP address to UDM Pro router, however, SIM mobile data modem RUTX50 provides different internet IP address than the public IP address. I believe it is not due to RUTX50 issue but due to different policies / technical arrangement of SIM mobile data connection as @roberttz described.

Static public IP address by Vodafone SIM mobile connection is more expensive than the ISP internet connection itself :frowning:

Is there any other technical solution possible (e.g. no-ip service which is much cheaper) how to solve it or just expensive Vodafone static IP address for mobile SIM internet?

Thank you all!


Depending on your needs, you could consider using VPN services such as ZeroTier or Tailscale, which don’t require a static public IP address. CGNAT, in general, is essentially just a double NAT controlled by your ISP. This means that the IP address starting with 46.x.x.x is not assigned to you alone but to multiple people sitting behind another layer of NAT starting with 10.x.x.x.

You could also ask your ISP if they could assign IPs to your SIM as in modem. It’s a bit of a long shot, but it’s worth a try.

Kind regards,

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