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Using my own router on FTTP when I have BT TV and double NAT issues

pduk — Tue, 12 Oct 2021 16:24:13 GMT

So many similar posts but struggling to find the one that answers my specific question (sorry it's probably somewhere but I can't find it).

I have FTTP with BT TV service. Copper phone line.

I use my own firewall device and I managed to connect it direct to the ONT and got it to work just fine except that it knocked out most of the TV service that is streamed (vs the free to air stuff).

So I connect the BT router between my firewall device and the ONT, and the BT TV box into one of the ports directly into the BT router. All works again except my kids can't play online multiplayer games, I believe this is a double NAT issue.

I've seen some threads about trying to get multicast protocols and ports (am I saying the right thing?!) working on my firewall to make this all work. But it was also unclear if BT TV servers are looking for their MAC address on their router as some form of access control to the service - I'm really unsure. But it would be preferred to somehow get this to work without the BT router.

As a final note, when my exchange goes digital for the landline I would consider stopping the phone line and signing up with another VOIP provider so to avoid any issues with being forced to use the BT router.

I'd really appreciate any guidance.

Many thanks

Re: Using my own router on FTTP when I have BT TV and double NAT issues

Keith_Beddoe — Tue, 12 Oct 2021 16:36:45 GMT

@pduk

BT TV is delivered using multicast, so if your firewall is blocking that, then it will not work. The BT TV will need to be connect direct to a home hub LAN port.

Re: Using my own router on FTTP when I have BT TV and double NAT issues

pduk — Tue, 12 Oct 2021 16:49:30 GMT

Hi thanks, have you managed to get this to work on your setup?
Seeing some of the threads i can't seem to find anyone that has got it to work, some cases where it indicates that more needs to be done then allowing it thru, but I've probably missed it.

Failing that, is there a way to overcome the double NAT with the BT router in between the firewall and ONT?
Many thanks

Re: Using my own router on FTTP when I have BT TV and double NAT issues

licquorice — Tue, 12 Oct 2021 17:01:09 GMT

Have you enabled IGMP snooping on your router?

If you connect 2 routers together LAN to WAN you cannot avoid double natting.

You can avoid double port forwarding by putting the second router in the DMZ of the first. No idea if that solves the problem with gaming.