Over the last week or so I have been trying to use my samsung A8 running android 9 to control my nd555 since the new platform allows multi apps to be used at the same time.
Often when I reach for the a8 while nthe nd555 is happyly playing and has just been controlled by the Apple phone, I start the Naim app on the a8, and get the cannot find any room message.
The solution on this phone in my setup seems to be to ddisable and reenable wifi on the phone. Suddenly my rooms show up as expected.
This seems to happen if the phone has been out connected to another wifi network and has moved back home or maybe even after a restart of the phone, this is a guess since I do not keep track on when this happens.
Fortunately Android is not my main mobile platform otherwise this would really make me want to give up Naim streamers!
This can of course be something specific in my setup, but as long as Android is not used my wifi is solid and my Apple devices rarely seems to cause more problems than showing the rooms screen, but not finding any rooms almost never happens.
Does your phone correctly sign into the home wifi automatically when you return? Should be easy to test by turning off mobile data on the phone, then try to open a website upon returning home.
(Edit: And if you have more than one network, go to the wifi settings and check which one it auto-connects to)