Sonos Arc/Amp with Sub: If all components are on Ethernet, can I disable Wifi?

You can, as far as I’m aware, but you’ll add a small amount of delay by doing so. How much depends on your network device, but the signal will need to come from the Arc and then go to the router, and then be processed to go to the surrounds and Subs. When connected wirelessly, they are sent the signal directly without going through the router (again). 
 

Whether you can hear that delay is questionable. The nice thing is you can test it with your Sonos, and if you don’t like the change, you can revert. 

Thank you for the reply, but that is the problem, I don’t have the “Disable Wifi” option on my sub when it is bonded and the Sonos app shows it is connected via Ethernet.  So my question still stands, why even have an ethernet port if you always have to use Wifi to bond to another device.  

I also understand the theory of delay that could be introduced, but also with Wifi, if you wanted a sub further away from an arc or amp, the wifi signal may not be reliable anyway.  

Now that we can turn SonosNet off totally, I was really hoping to get everything hardwired and turn off Wifi on everything to minimize Wifi interference in the house.  Seems like something that should be able to be done.  

You definitely want to turn SonosNet off in this case. The sub (and surrounds) bonding to the soundbar is done over a dedicated low latency 5 Ghz wifi that sonos creates for this purpose. You can’t turn wifi off without disabling that.

I never got my two wired home theater rooms to operate reliable when all were wired. I'd not recommend wiring anything, but if you must wire, wire only the Amp or soundbar.

I'm not sure what wifi interference you are hoping to eliminate by disabling the internal radio (that disable Wi-Fi actually does) in your Sonos. Are your 5 gHz channels all so congested your Sonos can't find an open channel for the hidden 5 gHz HT link?

What I would recommend is disabling Sonosnet so none of your wired, Sonosnet capable devices try to establish that on the 2.4 gHz channels. That leaves them able to create the needed low-latency 5 gHz surround links. VERY different than the disable radio (mislabeled Wi-Fi) option.

It is not recommended to turn off Wi-Fi for surrounds/subs, even if they are connected via Ethernet.  Though it sounds counter-intuitive, the custom wireless connection via a direct, one-way 5 GHz feed to surrounds/subs is faster and more reliable than Ethernet, which requires more hops, and can’t keep up with the low-latency requirements of syncing with video. 

I ended up wiring everything up, but left Wi-Fi on.  So far it seems to be working just fine.  The main issue I was trying to get rid of what drop outs when I had all of my players playing the same music.  Fingers crossed this keeps on working.  Thanks for the replies everyone.

Do consider disabling Sonosnet, it will remove the need for the 2.4 gHz channel it requires.

When watching TV I’ll get occasional dropouts on speakers grouped with the TV Sonos Room.  I have read there are ways to fix that in the app latency settings.  Have not fiddled with that yet.

I can’t hear the TV Sonos speakers when listening to the grouped speakers so the delay is not an issue.  The dropouts are so minimal I don’t loose any news info.  I’ll look at the settings later to see if the dropouts can be eliminated.

The only Sonos device I have on Ethernet is my Port.  WiFi is turned off on the Port.

Yep, SonosNet is off.  So happy they added that feature.

I didn’t get drop outs when listening to only one player (I’ve got about 8 sonos devices total), but only when I had the whole house grouped.  A single player or even a few together worked ok on wireless, but when they were all grouped, it was random which one would drop, but it would only drop for a few seconds and then come back.  Finger crossed this fixes it.  So far it has.