Sonos Amp becomes unreachable on UniFi after some time (no ping / no ARP, link still up)

You’ve read this thread? 
 

Don’t wire any SONOS units to the UDM PRO because it does not support STP. Yes, I know that there is an STP setting in the PRO, however, this is a default to be passed on to the switches. Set this for STP.

In my experience UBIQUITI updates can break things. Have you reserved IP addresses?

Yes, I’ve mostly followed these recommendations, especially the “golden rule”. All my Sonos devices are wired.

The only difference I noticed is that I was using RSTP instead of STP. I’m not sure if that makes a difference in a fully wired setup, but I’ve now switched to STP to match the recommendation and will observe if the issue occurs again.

All Sonos devices are wired to a UniFi Switch 24 PoE.

The affected Sonos Amp has a static IP address.

I already had a similar issue about two years ago and was able to resolve it back then. It seems, as you mentioned, that a UniFi update may have broken that setup again.

Changing the spanning tree protocol to STP and adjusting the switch priorities did not help. The issue reappeared after about one to two hours.

I once had symptoms that an ancient NAS was failing, but the symptoms were intermittent and not quite what I expected for a failing drive. After a while I decided that the symptoms suggested a duplicate IP address … but I’m too smart for that … right?!! Eventually I swallowed my pride and checked for duplicates … darn! A few weeks prior I had reconfigured my network slightly and updated all of the address reservations. Unfortunately, I had forgotten about a palm sized device hidden in a cabinet, using a fixed IP address that formerly had been outside the DHCP range. It now duplicated the reserved NAS address. This was certainly not UBIQUITI’s fault.

It is not related to the IP address. I started with a DHCP-assigned address and then moved to a different, static IP address. The problem stayed the same. 

Do you also have mDNS enabled? While I do not have my Sonos speakers on my trusted network, it is still enabled. May make a difference for you.

I also use RSTP with priorities set for main and downlinked switches. They should be set correctly if you have speakers wired to more than one switch.

There is also a great guide to check your settings with found here:

https://github.com/IngmarStein/unifi-sonos-doc

I ran another test to further isolate the issue: I connected a small unmanaged switch (different brand) to my UniFi switch, and then connected the Sonos Amp and another unrelated device (a printer) to that switch.

The result was quite interesting:

• the Amp disappeared again shortly after

• the printer remained connected and reachable without any issues

This suggests that the UniFi switch itself is not blocking the port.

At this point, I think there is a real possibility that the Amp itself is becoming unresponsive or crashing. However, I am not sure how to narrow this down further.

Has anyone seen similar behavior or has ideas for additional tests?

PoE can damage non-PoE devices like the Sonos Amp.  Not sure if that might be the cause of your intermittent connection issue.  I always use “dumb” non-PoE switches.

Different types of POE sources, some can be damaging while some are safe. Some source devices offer both modes and an error in configuration can be expensive.

Beyond my skill level but if you look for "standards compliant" and "passive" POE you should find details.

I suggest submitting a series of three diagnostics: one while the system is working, one immediately after the AMP goes offline, and one immediately after you get AMP back online, then call SONOS phone support.

As I recall, depending on the model, not all UBIQUITI switch ports will provide PoE and PoE can be disabled on a port by port basis.

See my response to your questions in the other thread, there is some duplication here.

Responding here, to avoid that duplication.

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That’s a good question. Back then I mainly adjusted a few UniFi settings, which improved the situation, but the system was never completely stable. Even at its best, I still had to restart the Sonos Amp roughly every couple of weeks.

I’m not sure what changed to make things worse now. It could be UniFi updates, Sonos firmware updates, or a combination of both.

Regarding WiFi: I also tested the Amp in isolation. I powered off the other Sonos devices and connected only the Amp via WiFi, with Ethernet disconnected. Even in this setup, it disappeared again after less than 30 minutes.