Actually, it sounds like a router issue, not one with the Sonos software. The first thing I’d try is a network refresh, by unplugging all my Sonos from power, then reboot the router. Wait a couple of minutes, then plug back in the Sonos devices. Wait another couple of minutes for the Sonos to reboot and reconnect, then test.

If, as I suspect, this ‘fixes’ the issue, I would certainly look at your router’s manual to set up reserved IP addresses, which will help avoid this issue recurring. 

IMO call support and see what they say. Unless you have all the time in the world to reboot your network and play network engineer

Bruce, is that a known issue, having to set up a reserved IP address?  Not exactly a tech guy so kind of I guess disappointed to hear that.

I’m sure that rebooting everything when it happens would likely fix it but the trouble is that I’m working at the time, on the VOIP, etc.  

It’s an issue with ‘some’ routers, and not a Sonos issue. The issue appears most frequently with Sonos, since each time the software/firmware on your Sonos devices (something that frequently occurs) the device reboots, and requests a new IP issue from the router. If the router has ‘lost’ its place in the DHCP table, which assigns IP addresses, it can hand out a previously used IP address, after which you can get ‘fighting’ between devices for the same IP address (data routing). It isn’t something Sonos is doing, it’s an issue with the router, and Sonos, as a client to the network, has no idea what is happening. Which is why a network refresh ‘fixes’ it, at least temporarily, and assigning reserved IP addresses (on the router, not on the Sonos) ‘fixes’ it more permanently. 

Essentially, when you do a network refresh, you’re forcing a reload of the router’s firmware, which reloads the DHCP table, and ‘resolves’ the potential for IP conflicts.

If other devices ‘rebooted/requested new IPs’ as frequently as Sonos did, you’d see a lot more of these types of issues on other forums. Sonos just happens to update more frequently than average, but they still are merely a ‘client’ of the network, and don’t have any control over the network itself. All they do is connect to it, per the standards set. 

And, FWIW (nothing at all), I have no idea why some routers can be affected. I’ve always assumed power surges impacting the firmware on the router, but that’s a guess. Could be poorly written firmware/software, I don’t know. I certainly have never done any research, but I’ve had, as far back as I can remember, reserved IP addresses for my Sonos. I’m pretty sure it was at the advice of one of the helpful posters on this forum which prompted me to take the ten minutes required to learn how it’s done. 

My current frustration is that the router I have right now (supplied by T-Mobile) doesn’t allow me access to do so…but I’ve also never run into issues with it. I don’t know whether that’s a better device, or the fact that my power goes out semi frequently , and forces a reload of everything. But if you can, it’s good network housekeeping, not just for Sonos, but all devices you have. I have, in the past, left the first 100 IP addresses unassigned, for floating devices (my, and friends phones, mostly), and used the upper range, 100 and above) to my ‘static’ devices. Never had an issue. 

Lightly edited, mostly for the inevitable autocorrect typos :)

This is a Sonos issue IME, not my router. If you call support they might still walk you through setting static dhcp but at least if it’s another issue they should be able to help you with it. 

Thanks a lot for this, I will give it a shot.

Really no need to call for support, either the router manufacturer, the best place, or to call or Sonos who likely don't know your router's internal settings. 

Log into your router, go to the DHCP settings page and follow the instructions there. Usually takes a few seconds per device ro add the IP address reservations.

Then power down all Sonos, reboot router and controller then power the Sonos back up. 

The issue might be Sonos or it might be the router but it is more likely an interaction between the two and possibly something else on your network. I spent many hours trying to pin down the issue but decided the many power cycles needed to make any progress weren't doing my Sonos any good. Just admit it is a possible issue and do the work-around and move on.

Okay guys, did the adjustment last night and reserved the ip addresses for all my sonos products within the router setup online.  So far, so good!  I didn’t have any issues last night and usually I was having to power cycle everything at least once every few hours.  Solution was even relatively easy for a goon like me to pull off.  Thanks again!

Great news, I really wish Sonos would prioritize getting this bug pinned down and fixed.

That they haven't feeds my suspicions that it is buried in the legacy Open Source code and that they don't have anyone currently on staff that has the skills to work in that space.

They don’t even acknowledge this bug exists though do they? 

Well, I really hate writing this... We were good for almost 2 weeks and my hopes were high.  The past two days have been mostly “can’t connect to server”, “can’t connect to speaker”, etc.  Typically I can get it to work for 1 song and then it stops playing.  Switched to bluetooth last night because I just didn’t have time to deal with it.  That’s after shutting everything down and plugging back in to reboot (router and also all sonos products).  IP addresses remain as reserved in the router setup.  It’s just too bad.

Time for a diagnostic submission and a call to support, you didn't get lucky and have it be the easy to solve problem we'd hoped it was. 

Seriously Call, far better chance of getting good support.