Eero and smart home devices
Most smart home devices only support 2.4GHz WiFi - presumably for better range reasons.
I don't yet have an Eero system but now that Amazon have released it in Europe I am considering getting a set.
It seems that Eero enforce the same SSID name(s) on both 2.4GHz and 5GHz. This means that there is no way to force an iPhone on to 2.4GHz. This is critical as it seems that most WiFi smart home products require the phone to be on not only the same SSID but also the same frequency in order for their app on the phone to be able to configure the smart home product. The app and phone when doing the initial setup establish an initial connection on a private WiFi SSID and then the app 'sends' the phones normal WiFi details to the smart home device, if the phone is on 5GHz then duh! of course it will not work on a 2.4GHz only smart home device.
This is I believe why some others in these forums have been reporting problems.
Now I get the impression even when using the same SSID names on 2.4 and 5GHz some other WiFi products manage to avoid this. In my own case I currently use different names for 2.4GHz and 5GHz networks even though they are both in bridging mode.
I would therefore prefer it if Eero allowed defining a different name for the 5GHz network. I can then force my phone to connect to the 2.4GHz whilst doing the initial configuration of a smart home device.
I’ve never really had an issue setting up IoT devices in the manner you describe (where they can only connect to 2.4GHz and initially are setup through your phone). I had one device that struggled, so I just took it and my phone to a point in my house farther from the nearest eero, and then my phone connected through 2.4GHz and I was able to successfully connect the IoT device. Wasn’t that big of a deal.