Most routers are both 2,4 and 5Ghz, but use the same network name for both frequencies. If you could “split” the the network, you give the 2,4Ghz and the 5Ghz a different name.

Another possibility would be the set up the same network name and password for your new router as you used for your old one.

Fine. I'm not technical and don't believe you need to be to listen to music. I have no idea how to split the network and don't want to use the same network name and password as previously even if this were to work. I have several other items requiring network set up and have no problems with them. As so many others have said this is a Sonos problem but this doesn't help me resolve my problem. I now have an expensive ornament.

Well, then, have you tried a call Sonos Support directly to discuss it? They’re likely more easily able to figure out your level of acceptability, and provide better answers that you might be able to deal with, for the issue you’re experiencing. 

I did try Sonos Support and wasted several hours. The agent blamed others for the problem and didn't provide any solution. I'm considering junking my Sonos and replacing it with something that actually works. It's been a lesson for me.