After a long day of trying to figure out why my Sonos Sub Gen3 was not connecting to my system, I eventually got on the phone with Sonos and they informed me my (very expensive) sub is not compatible with my SAX router from spectrum. So if youre like me and you are having issues connecting your sub to your system, check your router model and if you see SAX on it, they dont like each other. But Sonos is gracious enough to process a return for me so thats fine. But I am trying one more thing before I return it and I will update this thread if it does indeed work. They said the workaround is to connect it wired but unfortunately, where the sub is and where my router lives is just too far to connect that way. So I am ordering a wifi extender with an ethernet port built in. I will see if the one I get does help. It should be here in 2 days. If it doesnt work, Ill return both of them. Either way Ill let you guys know if this was a good workaround and what model ext i ordered.
I was never pleased with the box Spectrum provided to me in SD. I used it essentially as a modem only, and set up my own router, which I had more control over.
Using your own router and WiFi is a good idea when you have an ifrfy ISP supplied unit.
A less expensive but usually less capable alternative is to use a travel router to hook your Sonos and controllers to, then hook it to the iffy router.
I think the advice of both gentleman above (use your own router) will lead toi better results than you idea (a wifi extender with an ethernet port built in) as Sonos and exetenders als also hit and miss…..
Verdict is in! It doesnt work! Sonos, I have to return this sub, disappointing. I dont know if you're ever going to read this but in all my years with devices there is usually a redundancy for these types of situations. I do think its kind of remised that you made something with one type of way to connect to your system. I should be able to just plug and play this to my arc and be good to go. I don't understand why this has to be connected to the internet necessarily if I don't want it to. Ill probably switch out my router in the future but right now its fine for everything else so I'm not going to adjust for just one device. I'm going to have to keep up to find out if you ever work with SAX routers in the future so I can get it again one day. 
Sorry you couldn’t figure out a way to make it work, as it has for 99.9 percent of users.
I’m not familiar with the word ‘remised’ in this context. What does it mean?
Remised as in not taking care to do so/careless. Basically overlooking the fact that eh some ppl may need other ways to connect to it and not just internet. At the very least an audio jack would have sufficed. So now I am looking at other subs that will work with my current system. Cuz Im not going to wait 2+ years for this thing to finally work. But the arc is great, highly recommend!
Looking at this from the other side, why should SONOS hack the protocol in order to accommodate a wayward router? As SONOS developed the hack, they’d need to test it with all other routers. At some point it becomes an impossible task.
Only a SUB will work with ARC.
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