Are you saying the Arc Ultra by itself does not connect to WiFi when you get to that point in the new speaker setup process?

The Arc Ultra absolutely works via wifi.  I suspect your specific wifi setup isn’t supported or there is some other issue going on with the network setup.  It might be helpful to provide some info on your wifi router and any extenders/satellites you’re using.

Also, minor point, but there is only 1 generation of the Arc, and 1 generation of the Arc Ultra.  ‘Gen 3’ and Gen 4’ aren’t applicable to those two products.

You to get the Sonos naming  conventions right. There are no “Gen 3” and “Gen 4” devices as a category. There’s al Sub (Gen 4) now, but the Arc only has one generation and now has an Ultra next to it, so also in it’s first generation.

You were “realizing that these do not work via Wifi”. What do you mean? The newer Sonos devices won’t do Sonosnet so they need WiFi.

What faults did the system report connecting it?

I mean Arc Ultra is connected to WiFi but Sub4 and Era’s 300 cannot connect to WiFi in my living room System

 Are the 300s & Sub brand new?

All Arc ultra, Sub4, Era’s 300 are brand new, inclusive we tried to set them (sub4 and Eras) with Arc ultra connected to the router via network cable, the system have the latest update also.

Once I move again the Arc Ultra to my living room and back to Wifi the Sub4 and Era’s didn’t work again

 So the Sub & 300s were initially independently setup & connected to WiFi using the app?

II did all those step with Sonos support technician once Arc Ultra back to Wifi the Sub4 and 300s dissapear from the Sonos App, I didn’t had this issue with Gen3 lol

I think I fixed it, I had to factory reset all of them and set Arc Ultra connected via wired in my living room, once I finished adding the Sub4 and 300’s and updated to the latest version I have disconnected the network cable and now is working via WiFi, I hope this work permanently, thank you for your help!

It does not work with Android phone, it works if you have an iPhone 

I tried many times to connect to wifi but it would not connect.

After that i tried to conye with iPhone and it connected fine 

I couldn't get either the ARC or ARC Ultra to connect to my WiFi.  I changed from a Netgear mesh to a TP Link modem and everything works.  FYI, I saw in the trouble shooting that it only would connect to 2.4 Ghz.  Mine all connected to 5 Ghz. 

I also spent well over an hour with tech service with no solution.   The modem change idea came to me in the middle of the night.