The SONOS Apps are impatient. When you open a controller it attempts do discover SONOS units on the network. If response is delayed for some reason, the controller assumes that the unit is not present. After a while the controller will attempt discovery again, but by this time the human may have become impatient.

Being in the same room as a player is neither good or bad. The controller must communicate with players over the network. Both the controller and players might be dealing with network nodes in other, possibly distant, rooms. Likely you have some congestion on the network that is slowing response from the players.

If you describe your network for us, we can offer suggestions.

You can possibly fix your issue, or at least rule IP addressing out as a possible problem by setting static/reserved IP addresses for all your Sonos devices from your router’s DHCP settings page. That is usually simple and quick to do.

Once done power down all Sonos and reboot the router, then power the Sonos back up.

@BrianJ,

The ‘discovery’ of the Sonos products by the Sonos controller App can sometimes be a slightly complex area to explore, but briefly… 

SSDP (the UPnP simple service discovery protocol) is used to initially discover the Sonos players and is done via multicasting via UDP to 239.255.255.250:1900 and, for good measure, broadcasting to 255.255.255.255:1900. 

Both the Sonos players and controllers must share the same network subnet. However if the Sonos devices are connecting to multiple access points, the recommendations (from myself) are that they be set to the same WiFi channel and channel-width. This is for optimum performance particularly in groups and for some reason with some (not all) mesh-based WiFi systems, it appears some will work okay with Sonos, but others may not, particularly if the satellites/AP’s are perhaps auto-selecting their own WiFi channels. I’ve seen some people report issues with Google ‘nest’ mesh WiFi, for example, although others will occasionally say it works for their ‘small’ Sonos setup.

What is certainly not supported though by Sonos, are wireless range extenders, as some can mangle device MAC addresses and EoP (powerline) adapters.. so if you are using those type of wireless access points, to extend the wireless network coverage, then that may cause such intermittent device discovery issues by the Sonos Controller App.

Reserving the IP addresses in the routers DHCP reservation table can often help with device discovery, so consider making your Sonos IP addresses static. The router user-manual will normally assist you to do that in most cases.

Just to add aswell, it can sometimes be Apps/software running on the mobile ‘controller’ device that interfere with ‘device discovery’ Examples to perhaps consider are…

• VPN Client 
• Firewall software
• Antivirus software
• WiFi Calling/Dial assist
• Private network address (MAC address spoofing)
• Mobile data enabled for the Sonos App  

So consider disabling these features, even temporarily, just to see if that may fix your device ‘discovery’ issue.

The problem is your wifi router. Please tell us which one.

The speaker and the phone being in the same room is irrelevant: they don’t talk to each other (unless using AirPlay), they both talk to your router, and your router routes. Well it is supposed to, but in your case it doesn’t reliably.

Doesn’t communication still go through the router when you use airplay, since it’s a wifi technology?  Bluetooth would be a direction connection between the phone and speaker though.

Thank you Wise Owls of the Community.  It’s good to see the stalwarts still around from close-to-day-one loyally giving advice (though ratty seems less active now).

All of your advice is very welcome and, as ever, very helpful.  As it happens, after I had posted, the Sonos 5 reappeared.  What is frustrating is that this event took place, in effect, between Paradise songs; it did not occur on ‘start-up’ for a session.  The speaker just went.  Speaker to router distance circa 6 feet; phone to router distance about the same.

A while ago I did the fixed IP address allocation thing but a change of UK BT Hub 6 router (to replace a duff unit) and a new S5 (to replace a duff Play 5) meant I had lost those setting.  Time to embrace an IT faff and reset it all back.  

Sonos has, on the whole, been sound since Dec 06 when I bought the first components.  And the Quad (1990)-KEF (1999) combo play from a ZP80 from that original purchase without murmur.  

Thanks again all of you.

I am not an expert in Airplay, but I believe it has a mode similar to “wifi direct” where the devices communicate directly, not via the router (well unless wired of course). Its called AWDL (Apple Wireless Direct Link).

I do know that more recent versions permit hand-off, where after the initial connection the source device essentially hands a url to the destination and says “hey, YOU play this buddy” instead of transmitting the actual audio (or video) between devices, for a more reliable playback.