Having never had the problem, my nd5 xs is suddenly dropping out when streaming from tidal or Spotify. It’ll okay for around 6 seconds then drop out. Radio works fine.
It’s hardwired to my router and I don’t have the problem when I’ve tried my Cambridge Audio CXN using the same cables and connections
See the Tidal not behaving thread?
It’s the same with Spotify. When I go onto the Spotify app sometimes it finds the ND5, sometimes it doesn’t. I suspect it’s a hardware issue
Or maybe the Naim app?
pop it in the Tidal not behaving post mate
You don’t use the Naim app with Spotify.
I don’t use the Naim app for Spotify. When I use Spotify I use the option to stream to fire sticks etc and usually includes the nd5xs on the list but it show sporadically
It’s not a Tidal issue. It’s not connecting to my network correctly
Seems I’m not the only one and the problem isn’t just with ND5’s
Although you can if you choose to 
Just trying to elicit more info from the OP and trying to rule out potential reasons.
So what’s changed in your network? What router? Firmware update recently? Connecting with DHCP? Can you stream over your local network e.g. from a NAS or similar?
You can’t. Spotify can only be used with Spotify Connect.
In the Naim app there is an option for Spotify, so that’s my thinking. That said, I don’t use it.
Edit: I see now that it simply launches the Spotify app, so I stand corrected .
It will just take you to the Spotify app. They don’t allow third party access to their service, so Connect it the only option, other than Bluetooth or Airplay for devices that support it.