Do you have any other SONOS units?

Yes.   Several Play 1s, Play 5s, Playbase, sound bar and Sub

Only noticed this for about a week so must have been a software update.

I suspect that you have a bad network connection somewhere likely between the router and the switch.

If one or more SONOS units are wired to the network, they will build a private wireless mesh network known as SonosNet. It is not published in big letters, but SonosNet will share its connectivity. For example, if you have only one of your players wired to the network, all of the other network ports are connected to the network and available for 3rd party connections. Since SonosNet is designed for robust audio play, not speed, SonosNet is not blazingly fast.

I had almost exactly the same symptoms as yours -- low speed. In my case I had a switch with a computer, some NAS drives, TV, DVD, and a SONOS player connected to the switch. The switch was wired back to the router, along with more SONOS units. During a construction project, the wire between the switch and the router was damaged. The local SONOS unit figured this out and provided seamless connectivity to the switch -- but at a much lower speed than the wire.

When in diagnostic mode don’t assume that the problem must be t...] or cannot be t...], else you are likely to be blindsided.

OK.  Interesting.  Thanks.

Right now i simply disconnected the SOMO speaker from the ethernet are will use the WIFI.  I have a handful of other SONOS devices connected to the LAN directly.   

What is best practice here?   Just one SONOS speaker connected to the LAN?

Thanks

There is a general celebration that wires are gone forever, but I wire as many things (SONOS and other) as is practical. For me wireless is convenient at times, but never as fast or reliable as wired. In the case of MOVE or ROAM, wireless is the only option.

Actually, I’m moving toward fiber when possible. For the short term optical is more expensive and more trouble, but wire is running out of bandwidth, particularly for multiple 8K video feeds. Long term I think that optical is the way to go. For remodels and new construction pulling a fiber, even though it might be ‘dark’ for a while, is a good hedge against future developments.

I suppose that the 5G proponents will think that I am daft and 5G will solve all problems. We’ve been through this before where early adopters were very happy when new bands were opened, but eventually the masses moved in and clogged things. We are currently going through this with WiFi as a new 6GHz band is opening. 2.4GHz is very clogged and 5GHz is close behind. It is fortunate that range is relatively limited for these bands.