Just to add, if asked, I would currently recommend the DHCP reservation of all Sonos IP addresses.

In my own case I have the Sonos addresses ‘fixed’ fairly high up in the local subnet (out the way) at starting address 10.0.0.150 —> starting with the device nearest the router (150), then the next nearest device (151), then the next (152) and so on and so forth. I also keep a check on their SNR levels too, aswell as regularly checking the local network channels in use by neighbouring properties - it’s not a case of ‘set & forget’ as I do find the local wireless environment can change, particularly for the 2.4Ghz WiFi band. 

I find it hard to fathom why one would rather use various utilities to edit/maintain the static IP’s of each individual device on your network than use a singe UI in the router with all of the devices listed right at your fingertips, but what do I know?

I’ve had a variety of routers here, top of the line consumer devices to start, then Ubiquity and recently Netgate / pfSense gear. Sonos has IP related issues with all of them.

At this point I’m suspecting issues internal to Sonos, maybe some of their legacy open-source core code, that isn’t behaving well.

Thinking three different types of routers, running three different operating systems, all have the same issue is far less likely than it being a Sonos internal issue.

Some day I will get bored enough to dig out an Ethernet packet sniffer and see if I can see anything at that level as I’ve exhausted everything else I can think of.