Sounds to me like it’s return for a refund time, or accept you may have a rare ‘rogue’ and take a new replacement. Does everything else work as expected? Is it just Bluetooth that gives the problem? I ask simply because I’ve had almost 2 years of trouble free, every day usage of my Atom, but I only use it for streaming my own music collection from my UnitiServe by hard wired connection. I appreciate everything out to work as advertised, but there seem to be so many wireless variables these days it amazes me any of them are able to work 100% all the time.
I can understand your frustration, buy personally I wouldn’t buy a premium product and use a compromised connection method such as Bluetooth. I would at least use AirPlay or Chromecast which is likely to give better sound quality as well as a more stable network connection.
As others have found, I also find Bluetooth pretty unreliable whatever device I try to use it with. However, the fact that you need to hard reset by pulling the power cable out and then switching back on suggests something else may be at play here. I suggest you contact Naim support and give them as much detail as possible regarding the issue.
I know how frustrating it can be - I had times when I considered getting rid of mine but Naim have worked very hard to iron out issues - as timmo says above given the number of random devices things are supposed to work with its amazing anything works. Have you tried any different phones/tablets connecting to the Atom? Although like others have said above, I’m not sure that bluetooth is more convenient than just about anything except recording your own wax phonograph cylinders. Plus if that’s how you’re using the Atom day in day out it seems a pretty expensive box to buy for poor compromised audio. Do you have any subscriptions like Tidal/Spotify etc.? They are all native to the app and can be playing choons in less time than it takes bluetooth to connect, likewise Chromecast audio via Soundcloud or Google play music etc.