For people who may be looking in forums for answers: I had problems CONSTANTLY in the past with this. I have my network running on all Virtual Machines besides my access point which doesn't run any DHCP service. I had to make my router assign the Sonos Speakers on the network with a static address every time before I could get the system to stabilize. I believe the Sonos controller software revolves around IP address, so if you have a strange setup like me, I'd advise making sure your network has dedicated IPs for your Speakers. (May people say make sure one is plugged into the network, which has proven to help. This is a way to wireless accomplish the same thing).

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