Technicolor routers can evidently evidently be troublesome. It sounds like yours blocks STP traffic between its LAN ports.

To avoid this issue wire the system back through just one router port. Use a small switch or, depending on your arrangement, you may be able to daisy-chain through your Connect. 

Thank you for your answers. Do you know if I can disable the STP blocking on the router somehow? Do you know if there is a list of routers that are recommended for Sonos?

Matbe I will just keep it with just using one LAN port for Sonos as you suggest. I'm just trying to understand why it is not working using more than one port for Sonos.

A failure to forward STP traffic correctly is not unknown, especially in ISP routers. Under such circumstances when two Sonos units are wired across the router, on separate ports, the loop prevention algorithm fails to detect the wired path between them. As there’s already a wireless path, a loop forms and takes down the network with a broadcast storm. The only solution would be to hang the whole system off one router port.

Sonos doesn’t recommended compatible routers. The list of known incompatibilities which I linked is all there is. It’s also not necessarily complete.

Rather than hunt around for a different router, why don’t you simply add a 5-port unmanaged switch? They’re not that expensive at all. 

Thank you.
I have tried with different unmanaged switches but they caused the same problem.
My broadband connection stopped working as soon as I added a Sonos device.
Maybe the solution is to daisy-chain through my Sonos Connect or to buy a Sonos Boost. 

Most switches should be fine with multiple Sonos devices wired to them, then a single uplink connection to the router.

Which switch(es) did you try? Was it the same behaviour, i.e. wiring a second Sonos device triggered the problem?

My switches are TP-Link.

I think I will try with a switch again when I am back home next week.

Hello, 

Is it still recommended not to use switches with PoE for Sonos?

I have just tried with my TP-Link 5 port switch. Ithink it is a TL-SG105S. It seems to work but my broadband connection bacame a bit slow/unstable. Maybe it is just a c oincidence.

V4 of the TL-SG105S says it will “Monitor and address loop-related issues within your network structure to prevent disruptions caused by looping” which is somewhat concerning. Sonos’ own STP loop avoidance could be clashing. In fact, the switch might disable one of the ports feeding the Sonos units which would be unhelpful.

See how it goes. A storm is obvious from wildly flickering port activity LEDs. If the TP-Link doesn’t work well try a little dumb Netgear. 

I don’t see why PoE should be an issue either way. I’ve wired Sonos across a PoE+ switch without problem.

Thank you. 

Ok, I will see how it goes. Maybe i will try with a Netgear GS105GE, if the TP-Link causes a problem. 

I’ve several small dumb Netgear switches too, and they’re absolutely fine. 

Maybe a dumb Netgear switch could be the way to go for me. 

If you find it was incompatible hardware and the device isn’t listed you might tell Sonos support.

https://support.sonos.com/en-us/article/incompatible-network-hardware