Any details about your network? I’d guess there’s some sort of network issue, based on the fact that one controller can see them, but the other can’t. Have you called Sonos Support to discuss it?

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

All devices running the new Sonos app are no longer expected to be running the same firmware.

https://support.sonos.com/en-gb/article/legacy-product-update

However, you should still be able to see them in all controllers.

I’d first try force closing the iOS app and reopening to see if that re-establishes the connection to the Play:1s.

Thanks.

Unfortunately, we are on a Unifi network with multiple APs and that has always sent Sonos support out on a wild goose-chase regarding network setup.

Question is if there is no 17.4 firmware for Play:1 speakers but they are in maintenance mode now and thus not visible in the Sonos iOS and iPad app?

​@Mr. T : we’ve restarted all apps, iPhones and iPads on the latest app.

Noticed on one device that we use as a wall-mounted Home Assistant panel that we don’t use regularly for Sonos - opening the Sonos app, the missing Play:1 devices were briefly shown under system and then disappeared.

BTW - just tested - all units are shown in Sonos WebApp. Just missing in the iPhone and iPad apps.

There should not be any issue seeing the legacy products in the Sonos app, no matter how you are accessing the app.

I have older Subs that are still visible, as well as a Playbar and Play:3s, all of which appear when using the app on iPhones/iPads.

Although the Mac app can see them, I would try rebooting the Play:1s to see if that fixes their visibility on iPhones/iPads for you.