If you hook up a Sonos player to the main system, then take it out to the gym, it will work with whatever has previously been configured into it. Note that it will be divorced from the rest of the system because it's on a different network. Think of it as a 'clone', to seed the system in the gym.



You could wire the player to the gym router, attach a phone to the gym WiFi, and you're all set.



If you're going to run it in 'Standard Setup' -- i.e. on WiFi -- then wire it to the router temporarily and configure the correct WiFI details via Advanced Settings/Wireless Setup. You can then detach it.

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I would look at putting your music 'in the cloud'. I'm not an expert at the different options out there, but I use Amazon music. All of my stuff and playlist are there, and can be accessed from anywhere. So for you're setup, I would setup two completely separate sonos systems, both using a cloud service as the source. You wouldn't be able to sync your music in the house and gym at the same time, but I'm guessing that's not a concern for you.

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Honestly best bet would be to place a high power wireless access point on the furthest end of your house closest to the gym and have it broadcast the wireless signal to where you wont have to worry about having a totally different network there or you can extend the network out there but not by using traditional ethernet cable (CAT5E or CAT6) since the total cable length is 329 Feet. So you would need to run single mode fiber...but the cost of that is way more than what a really good high power wireless access point would deliver. Look into the Ubiquiti Power Beam series for building to building Wifi or just their AC Pro HD series for awesome wifi

https://www.ubnt.com/products/

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