I purchased a 50 foot Ethernet cable for temporary connections…which has been sitting in a cabinet for years now, but it helped me figure out a problem, so it was worth it. Remember, you’re trying to eliminate possibilities, not necessarily keep a permanent thing.
Another thing to remember is that your WiFi doesn’t exist in ‘a vacuum’. It is influenced by all sorts of things, some may not be in your control, much like when I had a new neighbor put a WiFi device that stomped over what I was using for SonosNet. Nothing changed from my side, it was an outside source of wifi interference. Things change in a network, not always able to be seen by you, from outside influences, to internal changes, such as updates to your router’s firmware, the Sonos devices, etc. There is no such thing as a static network, generally speaking. You’d have to make a huge effort to set up one, and it wouldn’t be smart, unless you were a company or government site. And even then, it requires monitoring, I’d think, and pretty constant at that.
And as I said before, getting great speeds are measurements between either the measuring device and your router, or extending to a server somewhere outside your home. It is not necessarily measuring the speed to or between your Sonos devices.
The extra time you mention does lend credence to either wifi interference , or a potential duplicate IP address issue. The diagnostic would be a good way to track that down, the hard data in it, read by a Sonos employee, might indicate which it is, or perhaps some other network issue.
One thing I’d certainly try is to check to see if indeed there is a duplicate IP address problem. Unplug all of your Sonos devices from power. Once that is done, reboot your router. Give the router a couple of minutes to come back up, and then plug back in the Sonos devices. If that speeds things up, you were suffering from duplicate IP addresses (I’d assume your router suffered from something like a power brownout, or a spike), and it might be worth looking at the router’s manual and setting up reserved IP addresses for all your devices. It’s good housekeeping for any network, and certainly wouldn’t hurt.
But remember, calling Sonos support after submitting a diagnostic is much more helpful than any response here, since our responses here can’t be based on hard data, like theirs are on the phone. We have to base our responses on our knowledge of networking, and the way Sonos works, without the support of the hard data.
