System updates always fail

Because there is something wrong with the way Sonos gear updates. So far nobody has pinned down just what is wrong but a work-around has been found and has worked well for a lot of folks.
There's nothing really wrong with the way Sonos gear updates.

Reserving IP addresses simply circumvents duplicate IP issues, typically due to a router that has been restarted and flushed its reservation tables. As Sonos devices reboot they request new IPs from the router, and get handed addresses that are already in use by other (non-Sonos) devices on the network.

Sonos is sensitive to the IP conflict issue because the devices communicate extensively between one another, which is significantly impeded if there are devices on the network with duplicate addresses. This is important during the update process where the controller driving the update needs to see the Sonos devices come back online successfully -- otherwise the update will fail.

There's nothing really wrong with the way Sonos gear updates.

Reserving IP addresses simply circumvents duplicate IP issues, typically due to a router that has been restarted and flushed its reservation tables. As Sonos devices reboot they request new IPs from the router, and get handed addresses that are already in use by other (non-Sonos) devices on the network.

Sonos is sensitive to the IP conflict issue because the devices communicate extensively between one another, which is significantly impeded if there are devices on the network with duplicate addresses. This is important during the update process where the controller driving the update needs to see the Sonos devices come back online successfully -- otherwise the update will fail.

Have you been able to actually observe a duplicate IP address issue with Sonos gear?

I have put many hours into perusing my router's extensive DHCP logs as well as monitoring the network with multiple different packet capture tools without observing a single instance of that happening.

Adding and removing the static/reserved addresses does impact the reliability of my Sonos gear, particularly during updates from the limited amount of data I've been able to collect but I have never once seen a duplicate IP issue.

Outside of updates always failing. My network fine. I've never had any audio issue from my system. This is just me dealing with my system for a couple of years. From what I've observed, it seems like the bridge is cutting a connection to the speakers before they've all finished download firmware.

Hopefully I got the quoting correct...

No, but my network doesn't generally suffer from this problem. Here's the thing, though: if the act of reserving Sonos IP addresses fixes update problems, then those problems must be related to IP conflicts, because that's the only problem that IP reservation helps with. (Or, it's a placebo.)

IP reservation does not just help with IP address conflicts (I note your change from duplicates to conflicts here) it also eliminates IP address changes when clients reboot or request a DHCP renewal.

The DHCP logs probably won't tell you anything, unless you collect them before and after a router restart and diligently inspect them to see if any IP addresses were handed out to a new MAC address before the lease belonging to a previous MAC address expired. You won't see anything that explicitly states 'duplicate IP' (obviously).

I have diligently collected my router logs for months on end and scanned them for Sonos related IP address changes. Nothing shown in the communications between the router and my several Sonos devices indicated anything related to IP duplication.

To rule out issues with other devices being the issue I have assigned every other device on my network a static/reserved IP to insure they are not intruding upon the Sonos addresses.

If you monitor the network you need to focus on ARP traffic. For example, Wireshark has a 'arp.duplicate-address-frame' filter that should find conflicts. If it doesn't find conflicts, you probably don't have any at that point in time.

I monitored that as well as several other areas looking for issues with duplicates and did not find anything. I have had the monitoring running for long periods of time trying to capture an issue during an update cycle and never caught anything. Not just duplicates but anything suspicious.

I was really just pushing back on the assertion that 'there is something wrong with the way Sonos gear updates'. Tens of millions of Sonos systems update perfectly, every time. Most of the people who own these systems have no need to frequent this forum. A small minority of systems will encounter update problems, reasons for which include IP conflicts, but rarely include any fundamental issue on the Sonos side.

Just because most folks don't experience an issue does not mean the issue doesn't exist.

There is something obviously wrong with the Sonos update process, just because it does not impact you does not change that. If there was no problem folks wouldn't be reporting problems and if it wasn't IP related in some way they wouldn't be reporting that the static/reserved IP assignment has fixed their problem.

I can't rule out that it is a duplicate IP issue but I have spent many hours trying to capture a duplicate incident happening and have not seen one. At the same time I have seen update failures that I can not explain when I allow randomly assigned IP addresses but have never seen a similar issue when I have assigned IP addresses.

Note: this is all IP v4 related, the Sonos gear does not appear to use DHCP for IPO v6 address assignement nor do IP v6 addresses appear to have any relationship to the update issues I am describing.

I've gone as far as reasonably possible for a customer to go in trying to identify the issue, actually a bit farther than is currently possible as Sonos has lately so severely restricted our access to Sonos internal data.

I do wish the Sonos folks would look into this as it seems to be a persistent issue for a fair number of Sonos customers. Even if they can't fix it, just adding a FAQ entry suggesting the avoidance option would be helpful.

https://support.sonos.com/s/article/2382?language=en_US

I'd hazard a guess that there is something going wrong with the Sonos networking towards the reboot end of the update process, possibly with the internal bridging of the connection methods. It can't be a purely Sonos issue though as it only impacts a small subset of users, so there seems to have to be some interaction with other customer equipment like routers or switches contributing to the issue.