About 20 devices came up on an IP scan. No Apple stuff in the system. No fixed IP on my laptop.

I have to assume a Sonos or a Comcast update broke it. I'll be going out there this week.

I plan to connect the blu ray first to make sure it is not blowing up the network. Then Sonos.

Fortunately I can hardwire each Sonos piece and turn the radios off.

I've done a lot of Sonos for a long time and read every thread I could. It seems clear that tech support has advised some to hardwire each piece, others to hardwire just the first one. Many here run them all to a switch, some the first plus daisy chain; I just run the first to a switch and SonosNet the rest. It appears any of these configurations are reliable in most situations. I have seen them all working fine in the field.

The new login bs is over the top and not installer friendly. They are always tiptoeing that line between installer friendly and installer hostile. Direct marketing is bad when a dealer has set it up.

How does one identify which device on the network is creating the storm?

The down and dirty way is to unplug everything from the network and isolate your laptop hardwired with the router. Then start running speedtests or ping -t and start plugging things back in and wait for speed to go to zero or ping times to go through the roof. It may take trial and error, and I would bring up the network backbone first (router, switches, APs) and then add in other hosts of the same type (printers, AV, Sonos) in groups. That way if like devices are creating a loop you'll be able to see it.

If you have the right kind of switches in the network you can see traffic stats per port and find the offending host that way but if your in the middle of a broadcast storm you likely won't be able to get to the switch web GUI. In a corp environment, a good IT guy with the right equipment would setup the network hardware on a management vlan and put all other traffic on vlans so the GUI is always accessible not matter what is happening on the other subnets.

Most managed switches have a protocol built in that is supposed to mitigate loops by watching for the same traffic across two ports and shutting down one half of one of the links. It's called STP and is what SonosNet is built on. You can tune STP to work and I've seen articles on Sonos help forums that show how to do this with certain switches. Or just pick a path and run all your sonos wireless OR run all sonos wired and turn off the radios.

I had a similar issue at a project that was pretty advanced. Multiple VLANS, Voip Phones, Several Cisco SG series switches, Lutron RA2, J+P video, Aruba WAPS, and a bunch of Total Control. Everything worked fine for 4 years! Then broadcast storms, zones dropping off, poor connectivity. After about 10 hours of trouble shooting with the top tier Sonos techs we actually found the problem.....a bad Sling Box.

This goes back to Shafer....start unplugging things int he network, wait a little while after you unplug the device, reboot the root switch, let the STP traffic build up, then submit diagnostics with Sonos. It was painful, but the damn Sling box was killing the system. It must have been an update in the slingbox because it would still work. This happened a couple months ago, and i have checked in on my customer a couple times since, and its back to working great.

Days like that make me really hate my job....

I seem to recall an older sling box install where it would create an ad-hoc network of its own and I couldn't figure how to turn it off. Showed up on my wifi scanner so I just changed channels around it. Similar to a modern wifi printer creating a network.

I found one once with this utility
https://www.wireshark.org/
I believe that it only shows activity on your LAN Connection.
I noticed alot of activity from a particular MAC address with it
then I linked that to a particular device with the UniFi Controller.