Router/Modem keeps changing bandwidth

I’d first look at what channel the router is set to. If it’s “auto”, set it to either channel 1, 6 or 11.  Then set the Sonos system to the same channel number, using Settings/System/Network. Most Sonos devices will work on both 2.4 and 5GHz channels. 

Unfortunately the router/modem does not give a channel selection at all. I was told by the cable TC tech the modem switches between the 2.4 & 5.0 on an as needed basis. I guess that means whatever device is using the WIFI router/modem the router/modem selects the better bandwidth for that device.

Can you give 2.4 and 5GHz different names?

That is what i was hoping to do. But the Optimum Cable Tech told me I could not do that either. He said I should go buy a separate Modem for my Sonos. 

I want to use only one modem.Router for all my devices.

Now if there is a dual bandwidth modem/router that will allow me to lock my Sonos equipment on the 5.0 GHz bandwidth that is fine. I simply do not know enough about this stuff; that is why I am asking the question.

Describe your network for us. SONOS models? Network switches? What is wired, wireless? Model numbers?

With respect to 2.4 or 5GHz for SONOS there is no great advantage forcing SONOS to 5GHz. If anything, keeping SONOS on 2.4GHz, removes some clutter for the 5GHz devices to struggle with. 
 

I have no experience with your Gateway, but it appears to have rather limited utility. Adding your own router would likely be an improvement and would give you better control. If possible, turn OFF the Gateway’s WiFi. If this is not possible, give the new router a different SSID (WiFi name) to the new router.    Wire only the new router to the Gateway. Don’t allow the new router to use *Auto” channel assignment. Use 20MHz channel 1, 6, or 11 on the 2.4GHz band.

Buzz: Thanks, My Sonos home theater equipment is brand new. It’s operated off the Sonos 2 app. I have a Beam, a Sub Mini, & 2 Sonos one speakers.

I have for the time being abandoned my Sonos 1 products, 2 Sonos three speakers because I just cannot get the Sonos 1 products I use for my stereo & music to stay online when I put on the Sonos 2 home theater system..

I love the wireless aspect of the Sonos system but am very frustrated no one from Sonos has been able to help me get the Sonos 2 Home Theater system working properly & no one has been able to tell me how to get both the Sonos 1 stereo system & the Sonos 2 home theater system up and running.

I know there is a way but i cannot figure it out, That’s why I’ve reached out to the Sonos community.

I plan to go out & buy a router but still not sure what router to buy.

Thanks

Buzz:

The Both the Sonos 2 home theater & the Sonos 1 stereo are wireless. I do not have anything hard wired.

I do not purposely switch networks. it seems the router/modem does that without my knowledge. There is no setting to lock that either.

Here is the S1/S2 compatibility list. If all of your units are S2 compatible, moving everything to S2 would be your best plan. Before attempting to move to S2, do you have any SONOS playlists or music service registrations that should be transferred to S2?

You might be able to keep the modem/router /WiFi thing you have now but switch off the 

WiFi and set it to Bridge Mode, then you can add a WiFi enabled router (no modem) that won’t be doing such odd things.

Another option is to just disable the WiFi and plug an Access Point into one of your Ethernet jacks, let the AP do your WiFi.