Changes to Swisscom IPTV? (third-party router)

I have a setup here: FTTH <-> Internet box standard <-> third-party router (NAT, firewall, IGMP proxy) <-> VLAN <-> HD TV box.

When configuring the third-party router, I followed the following two articles:

SWISSCOM: Settings for third-party routers

TuxOne: pfSense 2.1 with Swisscom Access

TechIsland: Swisscom FTTH without internet box

Thanks to the third-party router’s IGMP proxy, Live IP TV ran, even without the IB’s DMZ.

Then I changed something and I can’t get it back to work. Neither with nor without DMZ. Unfortunately, I don’t see any signs in the third-party router’s log that any needed traffic is being blocked; neither from NAT nor from the Stateful Inspection of the FW.

Now there is the possibility that I did not reverse the configuration cleanly and simply cannot find the configuration error.

Or something has changed on SC’s part.

That’s why I’m first interested in whether everything still works as it should for other customers with third-party routers?

A third possibility: Because my firewall has to be set differently than in the linked articles, there may be a change somewhere that is only noticeable to me. Unfortunately, there is extremely little information about what data traffic really needs to be enabled. This can only be seen to a limited extent from the FW rules.

Turning off the FW doesn’t work because permission for the multicast addresses can only be granted there.