SONOS compatibility: [Link: support.sonos.com]

While I haven't encountered a Comcast Gateway that touted Gigabit speeds, I haven't had any trouble with network loops. I don't know if special Gateways are used for Gigabit. I have installed Gateways recently mailed to customers for self install. None of them has been labeled as DOCSIS 3.0 or 3.1.

I wire as many SONOS units as practical and I may run a few wireless. I know some installers seem "always" to have trouble, I'm at the other end of the spectrum at "never". I've never turned OFF a radio.

I do pay attention if there is a managed switch: Enable STP, not RSTP. Jumbo frames are not welcome.