Which products are you using? Describe your network for us -- router, access points, network switches. Are any SONOS players wired? Are you using a BRIDGE?

If you are using managed network switches, make sure that they are configured for STP, not RSTP.

Just Sonos Amp. WiFi router. I don't use any switches. Everything connected via WiFi. Even Sonos. Everything works. But when I connect my router (LAN port) to Sonos via ethernet cable (cable is fine), the network is going down. I was thinking that there is something in the Sonos Amp configuration (something like in airport) but I see nothing like that in menu.

I tried yo connect my TV with cable to router. It works

Unlike an Airport, AMP cannot function as a router.

Submit a SONOS diagnostic and post the confirmation number here. SONOS support has access to setup data. Send two diagnostics, if possible -- first, send one using the WiFi connection and another while using the wired connection. If you cannot submit a diagnostic in the wired configuration, remove the wire and send another using WiFi.

Which model WiFi router are you using?

When you say that the “network failed”, are you saying that other devices on the network stop functioning, or only that you lose contact with AMP?

242037612 first (via WiFi)

982123199 second (with cable. But I can't see Sonos now. And there is no Sonos in my network)

This time network is working.

I removed the wire and the system started immediately

Router model is ZTE F670

Hi!

Hello! 

Could you please tell me, if I turn off the WiFi connection in settings, may be the wire connection will begin to function? If not, I am afraid to lost the access to Sonos