Making contact with home network when DSL down

I would like to make remote contact with my home network when the DSL connection is not working.

Is the a mobile network which does not use CGNT?

Or another way of doing this? (aside from having a second line.)

Try THREE data SIMs using the "3internet" APN - which used to not use CGNAT.

Other mobile networks only offer no CGNAT to enterprise customers I gather.

Some paid expensive remote control services can bounce you through a cloud, into your home PC - but not suitable for VPN into your home network.

AAISP do data SIMs with no NAT and a static IP.

Thank you for both of the suggestions. I have encountered another problem:

I have a Huawei E3131 USB stick which I am trying to use with a Zyxel VMG8924-B10A router.

When I connect the stick to my laptop it generates a web page and I have to click 'Connect' to establish a connection. Ok when I am using the laptop.

If I connect the USB stick to the router, the 3G connection is activated if the DSL line is disconnected. But if you then try to access the internet via the router you still end up with a web page where you have to click 'Connect'. OK if you are on site but a bit of a problem if you are not there and want to establish a remote connection when the DSL connection is down.

Do all sticks work like this?

I've used a few Huawei sticks - most recently an E3131 as you have yourself.

I'm pretty certain while it has a 'connect' button in the interface, there were also options in the settings to connect on demand, or maintain connection permanently. Anything like this on your one? Mine was unbranded/unlocked so dunno if it's the same firmware.

Last time I used it as a network gateway however (when someone decided to crash their car into my FTTC cab!) I was using it on a raspberry pi where it simply showed up as a USB ethernet adapter and it 'just worked'.

I think most routers that support 3G/4G USB fallback would be capable of making it connect anyway though. May be that there's a setting to say only activate when primary WAN is down in the router itself.

Thanks for your reply. The E3131 I have does indeed have an option to always connect and it does look like the 3internet APN does not use NAT, so many thanks to all for those points. The only problem is that if I try to access the IP address of the stick what I end up with is the stick's web menu page. What I would like to get to is the router's maintenance web pages, or another device on my home network.

Ok so progress...

Is there any kind of port forwarding or DMZ feature on the E3131 interface to pass ports through it to the router?

I've not got my E3131 to hand (also no SIM for it..) so can't check that kind of thing I'm afraid.. so my helpfulness may end there. What I do remember of the interface is that it was pretty basic. I don't recall there being lots of options so you may be out of luck..

Might be some setting on the Zyxel router perhaps.. I don't know that model.

May also be you need to switch the E3131 into 'modem' mode for the router to handle the connection... Google it, but be careful if you're not comfortable around command lines. You may also conceivably put the stick in a mode you can't easily recover it from - not broken, just stuck in a different mode. Again, I'm not sure if that will work, it will no doubt take some experimentation, what you're wanting may simply not be possible.

Also if the model interface is accessible over the 3G connection then definitely change the login information assuming that's possible!

I have been trying to switch the dongle into modem mode but I can't establish a serial connection to the com port that I did manage to get it to create. The stick does rather predate Windows 10 and my laptop does not have a proper serial port of its own which might help.

You may want a newer stick. Most create a software USB port in their windows or Mac drivers, so how they work with routers like your Zyxel is unclear.

The sticks are modems. No modem mode on them. Raw Cell network IP delivered to your Zyxel or PC it's plugged into.

When I used it on my raspberry pi it presented to the system as an ethernet adapter (popped up as eth1) with an address in the 10.x.x.x range and as a proper network with gateway..