Port forwarding has stopped working

[boydwill]

Since January 2022, I have been running several "sandbox" websites on raspberry Pi webservers.

These have been accessible over the Internet using a reverse proxy server to a) manage SSL - using Lets Encrypt b) share traffic to multiple websites and c) handle the non-static IP address of my router  - using duckDNS.

I also have a NAS drive with Internet access.

This all stopped working about two weeks ago, because port forwarding had stopped.

DuckDNS is still tracking changes of IP address, but because ports: 80 - http, 443 - https and 9000 - NAS access, are all closed I cannot access the websites or NAS drive, and SSL certificates cannot be updated. 

The modem/router is a ZTE MF286D 4G router.

I checked the router settings - all OK

The APN is 3internet

Testing with  https://portchecker.co shows all ports are closed.

Has 3 changed anything in the network recently that would block port forwarding?

Regards,  Boydwill

[boydwill]

Hello Jonathan, after having no success using webchat, I telephoned Three technical support.  They understood the problem, asked me to switch off my router while they made some changes, switch router back on and problem was solved.  No changes in my router settings.  I asked what had been changed, he said it was to do with the rollout of IPv6.

portchecker showed that ports 80, 443 and 900 were open. 

Let's encrypt renewed my SSl certificates

DuckDNS routes requests to my "public" IP address

However a traceroute to my public IP address still failsI 

I am happy that normal service has been restored, but still curious about the technical details.

Thanks for your help

boydwill

[JonathanB]

Hi @boydwill,

I'm sorry for the delay in getting back to you on your post and PM. We do support port forwarding and 3Internet shouldn't be employing CGNAT.

We've seen a few issues cropping up as we ramp up IPv6 on the network, as we've mainly been on IPv4 till recently. I don't think we've had this exact scenario, but I do wonder if this is similar to FYI : IPv6 Prevented VPN Connection 

If the APN is detected automatically, set a manual APN profile, still for 3internet APN and set the router to IPv4 only.

This seems to be helping with some device and VPN connectivity issues, so I wonder if it solves this too?

Thanks,
Jonathan

[PaulieP]

I know this is an old post but brilliant advice,  this worked for me.

Was pulling my hair out with the router stated wan ip not matching the detected ip via web 

[snoopy]

Problem solved!

For some reason I've mixed up NAT with Firewall ☠️

https://community.three.co.uk/t5/Broadband/Three-Zyxel-NR510E-5G-router-DDNS-and-NAT-port-forwarding...

Server works now, but still cannot ping it from outside 😅

I will try to work it out later on.

[snoopy]

I am just pulling my hair out right now. I've done everything as above and it is still not working 😪

Or should I add new APN? I've just edited first one.

[JonathanB]

Welcome to the Three Community @PaulieP!

Glad to hear this older post was able to help. It's one of the great things about having a support community, even info that's a few months old may continue to provide help and advice. Thanks for taking the time to confirm the solution is still working.

Thanks,
Jonathan

[Larnu]

This was exactly what solved my problem. I went to 5G settings -> APN and then set up a new APN called "3internet IPv4 only", set the PDP type to IPv4 and then the APN to "3internet" and suddenly all my port forwarding came to life (after renewing my DDNS).