Do you have experience with the Cisco SG250X-24P-K9-EU switch?

Which Ubiquiti switch are you talking about? There are different models. I have two ES-24-250 Watt and they also support Layer 3 routing.

I didn't know the product line at all. I only knew the white ones. But I also don't find their site really accessible... Does it support IGMPv3?

I am always in favor of simple solutions:

Why don’t you just leave out the USG?
FritzBox + any switch? Nowadays everyone should actually support IGMPv3, or am I mistaken?

Or simply connect the TV directly to the FritzBox.

I am always for simple solutions: Why don’t you just leave out the USG? Fritzbox + any switch? Nowadays, everyone should actually be able to handle IGMPv3, or am I mistaken? Or simply connect the TV directly to the Fritzbox.

Of course, that works. I already wrote that just now. I don’t understand what all the fuss is about here.

I am always for simple solutions:

Why don’t you just leave out the USG?
Fritzbox + any switch? Actually, nowadays everyone should support IGMPv3, or am I mistaken?

Or simply connect the TV directly to the Fritzbox.

Actually, I have also considered wiring the FB directly. It just doesn’t satisfy the nerd urge.
As for IGMPv3, I would have thought so too. On the other hand, it doesn’t always seem to be the case. The Unifis apparently don’t support it. The Edges, which I didn’t know until recently, apparently do.

Actually, I have already considered wiring the FB directly. Just doesn't satisfy the nerd urge. As for IGMPv3, I would have thought so too. On the other hand, it doesn't always seem to be the case. The Unifis apparently can't do it. The Edges, which I didn't know until just now, apparently can.

I don't know the Unifis but my MagentaTV receiver is connected to a 25€ Netgear GS108GE 8-port switch and works perfectly.

Yep, it does here too. In the new house, however, the NW should not run over dozens of different switches.