If the problem is the router, get a Motorola cable modem/router. I have Spectrum internet and my 11 Sonos devices work great with my Motorola router.

Thanks! While it’s incredibly impressive that you have almost 10,000 posts on this Sonos product support forum, that’s not one of the options here. 

I might be able to convince my dad to get Spectrum to replace his router, but I don’t think I actually will. What I’m really after in this thread is one of two things:

1. Someone offers suggestions for troubleshooting this from our end.
2. a representative from Sonos explains why they don’t support a common router that tens of thousands of people in the US use.  

If neither of those options appear, I’m confident I can get him up and running on a non-Sonos product easily.

When I was forced to use Spectrum, and before that AT&T, I chose to use the provided equipment as a portal only, and supplied my own Netgear for internal use, something that I had much more confidence in, much like @GuitarSuperstar . 
 

As to your second question, I’d suspect a Sonos Forum moderator will not be able to provide you an answer, since they’re unable to have control over all routers that are made. The simple fact is routers that are ‘provided’ by ISPs tend to be a least cost item, dictated by bean counters. I suspect Sonos has designed to use the published network standards, which all devices are supposed to match, but some appear not to, as they add special ‘features’ to differentiate themselves or do cost cutting and remove features that they think most people won’t use, in order to save a cent or two per device, which makes a significant difference at scale. 

All that being said, your father’s issue is the first I’ve heard of problems with this model. Beyond your suggestion, I’d also try setting up reserved IP addresses for both this Sonos device, and your father’s phone. If there are any other common network devices, give them reserved IPs as well, it is just good housekeeping. 

While I’m not a huge fan of Customer Service roulette, I’d be tempted to try calling in again, to see if you might find someone with a bit more knowledge, and less reliance on reading a script. You might also, after that, try posting a system diagnostic here, and hope that a forum moderator has the time to look at it and offer an analysis of what they can see. 

I am having the same issue and have been told that the SL1 speakers are not compatible with the Spectrum Sagemcom router Model # SAX1V1S. (I have no problem with the Sonos Play Bar and the Spectrum Router). Unfortunately, the Sagemcom routers are all that Spectrum offers.  I have purchased a Ptp-link Router and will see if that hopefully addresses the issue. You would think that the largest ISP in the country and one of the major audio systems providers could be on the same page.

That seems unusual to me. Who indicated that these Sagecom routers won’t work? It’s true that you must be able to set up the speaker first, before ‘bonding’ it to the Sonos soundbar, where it gets its ultimate connection from. 

Remember, there are two steps to setting up surround speakers. First, you set them up as normal ‘rooms’ in the Sonos controller, then you ‘bond’ them to the Sonos sound bar. At that point, they connect to the sound bar, and not your WiFi signal, and get their IP addresses from the router as proxies through the sound bar. 

When I was with Spectrum, I used their ‘router’ as a gateway, turned off the WiFi, and connected my own Netgear router to the WAN connection. I also never had to set up new surround speakers during that time, so I can’t attest to whether or not they can be set up using Sagecom. The ones I already had just worked.