My head is spinning.
Refrain from Factory Reset of any SONOS units without further consult. As you have discovered, this does not usually resolve fundamental issues.
If both Eeros are setup as routers I can imagine that you would experience something similar. Only one Eero can be the router, the other(s) must be configured as mesh points. If you carefully follow the Eero setup instructions, this detail should be taken care of. Is the upstairs Eero wired or wireless?
Describe your network in more detail. Are there any network switches? Which Gateway or Modem are you using? There should be only one connection to a Gateway -- the first Eero and this Eero will be the router unless you have specifically configured none of the Eero’s to be a router.
If you can, put the Gateway in “Bridge” mode. If you cannot do this, make sure that the Gateway and Eero are using different WiFi credentials and remove the Gateway WiFi credentials from all of your devices. In this configuration the Eero wired to the Gateway will become the router.
“WiFi” and “wireless” are not equivalent. If you wire one or more SONOS units to your network, SONOS will form a private wireless mesh network (“SonosNet”) and ignore WiFi. WiFi will also ignore SonosNet.
If you have discovered how to turn OFF SONOS “WiFi” turn it ON again. There are specific use cases when turning OFF SONOS WiFi can be productive and yours is not in that bin. In your case there will just be mayhem.
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As you have connected the SONOS system, the upstairs units will depend on the downstairs units for their connectivity and this will be done wirelessly over SonosNet. If your house is very dense it’s possible that the upstairs units are out of range. We don’t know this yet, but just keep this feather in your cap.
If you’ve been Factory Resetting SONOS, let’s check and make sure that they are one, not two systems. On your SONOS controller go to Settings → System → About My System and make sure that upstairs and downstairs are using the same Sonos ID. While you are on this screen make sure that all of your SONOS units are shown as WM: 0.(This indicates that the unit is using SonosNet. WM: 1 units are using WiFi. Things get messy if your units are mixed between WM: 0 and WM: 1)
Thank you @buzz for the response. Sorry about the head-spinning effect :-)
You response was helpful. Here is what I ended up doing:
If both Eeros are setup as routers I can imagine that you would experience something similar. Only one Eero can be the router, the other(s) must be configured as mesh points.
It was setup as a Mesh from the beginning. No change here.
Is the upstairs Eero wired or wireless?
Upstairs is Wireless.
Are there any network switches? Which Gateway or Modem are you using? There should be only one connection to a Gateway
No switched or Gateway. However, the Internet Service Provider (ATT) Modem was a router as well. I had given the SAME network name and password as the Eero Mesh. This is where I had to create a new network for ISP’s network and Eero’s network. This solved most of the issues.
If you can, put the Gateway in “Bridge” mode.
Not necessary. I kept it in Automatic mode.
“WiFi” and “wireless” are not equivalent. If you wire one or more SONOS units to your network, SONOS will form a private wireless mesh network (“SonosNet”) and ignore WiFi. WiFi will also ignore SonosNet.
Question for you: Is this by “Disabling Wi-Fi” on the Sonos devices?
If you’ve been Factory Resetting SONOS, let’s check and make sure that they are one, not two systems. On your SONOS controller go to Settings → System → About My System and make sure that upstairs and downstairs are using the same Sonos ID. While you are on this screen make sure that all of your SONOS units are shown as WM: 0.(This indicates that the unit is using SonosNet. WM: 1 units are using WiFi. Things get messy if your units are mixed between WM: 0 and WM: 1)
If the upstairs Sonos is not showing WM: 0, what do I do?
Overall, Im good with the setup. However, the caveat is if I am downstairs and move to Upstairs, I need to disable WiFi on my cell and enable again to show ONLY the upstairs Sonos devices. Though my cell phone is connected to the Upstairs route (checked using Eero → Connected Devices), I have to physically disconnect, close Sonos app and enable and open Sonos app. Do you have a solution for this?
I wish that SONOS would change the definitions that they use for that “Disabling WiFi” option because it actually turns the unit’s radio OFF. In this mode the unit must be wired and it will not support SonosNet. or WiFi. The SONOS ROAM and MOVE do not use SonosNet, they are WiFi only (WM:1).
Check your SONOS Settings and make sure that all of your SONOS units are using the same Sonos ID.
If your house is very dense, downstairs SonosNet units might be out of range for the upstairs units and break SonosNet. This can create a mess for SONOS in an Eero mesh. Eero can push wireless clients from WiFi channel to channel and this will freak out the SONOS units.
As a quick test you could bring an upstairs SONOS unit downstairs to make sure that it connects to the downstairs units. Temporarily wire the the unit if necessary and straighten out Sonos ID and WiFi setup issues. If the unit then does not work upstairs, there is a signal strength issue that you should ;be able to work through by adding a BOOST at a strategic location or moving one of the downstairs units to a location that can support upstairs SonosNet units.
Thank you @buzz for the quick response! Another helpful and detailed reply. I will try this out this week and confirm. I’ve been thinking abt Boost due to the layout and distance between downstairs and upstairs unit.