I'm following this story with great interest.
I've a wired ND5 XS as part of my main hi-fi setup, a wireless Mu-so Qb and 3 SONOS things (Connect wired, Plays are wireless). Over the last 10 years, the SONOS never stopped playing or dropped out. Note that I'm listening at least 8h/day to streaming audio (internet radio, ripped cds on a NAS).
I own the ND5 since 1,5y, the Mu-so since 6 months. Using iRadio, the ND5 nor the Mu-so ever stopped playing.
Using UPnP is another story... I'm facing approx 2-3 "Stopped" playing situations at random in a week time.
As already mentioned here above; there's indeed more than just the Naim gear. It is also the router/switch, NAS etc.
Over the last 10 years, I'm on my second Lacie NAS (Cloudbox 2TB - 159€). The thing is pretty basic, not powerful at all, but it is dedicated to stream music to the SONOS and/or Naims; something that works pretty well. No - it is not fault tolerant, but as I'm in IT, I've 4 copies of my music collection by "a click on a button" on different machines, on different locations, so this would be sufficient
However, my wireless router, a Netgear WGR614v9, nearly 10 years old, and also pretty basic (39€), is in my opinion the weak piece in the chain. I don't suffer from the "Stopped" experience when my children are not connected to the Netgear to watch Youtube movies. It all started with the fact that the "Stopped" behaviour only showed up 1) in the evening & 2) during the weekend. Never during the day when I was the only one at home. 1) & 2) are the timeframes my children make extensive use of the router and demand high volume and hight throughput.
I'm thinking on redesigning my network infrastructure at home, so I can live with it for now, but I'm quite convinced it is the router.
But having said that, on the same router, the SONOS never dropped out. ;-)