[SOLVED] Problem on switching router to mobile

[gtsolid]

Hi,
i have a vodafone station and it has a particular behavior.
It's provided with a back-up USB key with a SIM card and, if the normal connection from RJ11 cable has faults, the SIM card switch on.
But in this case i lose the network devices shared with the external parts (eg. cameras and mail).
I use a DynDNS account and it seems the IP is updated (i used a ping test). What can be the problem?

 

[kanewolf]

Hi,
i have a vodafone station and it has a particular behavior.
It's provided with a back-up USB key with a SIM card and, if the normal connection from RJ11 cable has faults, the SIM card switch on.
But in this case i lose the network devices shared with the external parts (eg. cameras and mail).
I use a DynDNS account and it seems the IP is updated (i used a ping test). What can be the problem?

You probably don't have a public IP address when you switch to cellular. You may have an IPv6 private address -- https://en.wikipedia.org/wiki/Private_network

 

[gtsolid]

Yes, but the DDNS should avoid the problem, because i have installed a software for communicate to DDNS the current IP.

 

[bill001g]

DDNS just change the IP that is associated to text url string. It has nothing to do with public/private ip.

You need to check what IP address is being assigned to your router from the ISP when it is running on mobile broadband. Although you can look up what ranges are private the easier way is to compare what you see the router thinks it has to a site like whatsmyip. If the ip addreses are different there is a nat router in the path and you likely have a private ip address.

There is almost zero use of a public IP for mobile phones so the vast majority of carriers do not provide public ip. Yours might but you need to see.

 

[gtsolid]

Actually i can see the same public IP both in the router page and in whatsmyip. I think it's all i need, right?

 

[bill001g]

You are lucky I guess it is pretty rare to get public IP.

What happens if you reboot the router and have the initial connection come up via the mobile broadband. All I can think of it is the router does not switch the port forwarding rules correctly.

Although not recommended for other than testing what happens if you enable the router to be configured via the wan. It you go to say port 80 from the internet do you get a prompt from your router to login.

 

[gtsolid]

All I can think of it is the router does not switch the port forwarding rules correctly.
It you go to say port 80 from the internet do you get a prompt from your router to login.

I think so, it could be a port forwarding rule not working. using external tool i can see some TCP ports are open, but UDP 500, for example, is closed, even though it's opened in the model page.

All i have for a remote configuration is "Allow ping to WAN interface", but i cannot reach the page from internet activating that option

 

[bill001g]

Although you don't want to leave it on long term try using the DMZ options instead it is much simpler than port forwarding. Remember to be considered open a port must both be allowed by the router and there must be a program listening on that port that will respond to the scanner.

Note udp 500 is one of those special ones, not sure why it would not be open. In any case UDP 500 is used as part of a IPSEC vpn tunnel. Port 500 is not the issue. It is that the router must also allow PORTOCOL 50 though. This is a special feature many devices have but many also do not document it. If you are attempting to use ipsec vpn it is adding even more complexity to what you are doing.