Naim/ Tidal app

I am finding this app increasingly unreliable. Can anyone suggest an alternative? I have 4 musos in my system

There are no alternatives that can perform all of the functions of the Naim app. Some things can be controlled using Airplay or Chromecast if you use various music apps on a phone or tablet, and Spotify or Tidal can be controlled using the Connect function within their own apps, and many functions can be controlled from the Mconnect app but there will always be times when you need to use the Naim app.
You don’t say exactly what problems you have experienced with the Naim app, but chances are you have some sort of network discovery issue which you may be able to resolve rather than giving up on it.