adding new sonos to app

Try rebooting your router and phone.

If that doesn’t help, try wiring one of your speakers (not a Sub or surround) directly to the router with an ethernet cable.

Thanks . 
I will give that ago , can you tell me why when I add them it adds to its own Sonos network but Then try’s to connect to my talk talk WiFi (this fails) but where is the Sonos network as they still cannot be found even tho it’s tick 

obviously I need to try Ethernet cable , just wandered where the Sonos network it located as it’s not in my setting on my phone nor on the app 

SonosNet is not a discoverable WiFi signal. 

Is it possible that you accidentally setup the new units as a ‘new’ system, rather than adding them to your current system?

I clicked add product it finds it after I reset the Sonos adds to the Sonos network (whatever that is as I can’t find it on my settings) but it won’t connect to my internet for some reason (not had a problem before ) I did manage get one set up but changed the room name then it disappeared. I not sure if the app is playing up as my beam sub and 2 play ones are missing from app even tho they are working through my tv . 

oh right so What is it then ? I’m trying to learn about this system sorry if I sound a bit stupid 

SonosNet is a hidden wired and/or 2.4Ghz wireless (in-built) mesh network, exclusively used by Sonos products that supports STP - The spanning tree protocol. 

It’s not something you will normally see to connect your mobile device to. 

It’s initiated by wiring one, or more, Sonos devices to the LAN router. The routers DHCP server handles each Sonos device IP address, some of which are proxied in some instances.

Sonos ‘portable’ products (Move/Roam) however, do not use the SonosNet mesh system, but use the local router WiFi instead (2.4Ghz or 5Ghz WiFi bands). 

To switchover all ‘non-portable’ Sonos devices in a system (household) from SonosNet (wired) to the local router WiFi (wireless), you ‘usually’ need to uncable all Sonos devices from the LAN and the system will then use the trusted local WiFi network SSID/credentials instead, that you should see in the Sonos App ‘Settings/System/Network/Manage Networks’ area. These credentials are stored on each Sonos player. (The Sonos App is just a remote and amongst other things, views information stored on the Sonos products)… and so if changing router etc. the SSID/Credentials can easily be changed/updated (when wired) using the ‘Update Networks’ feature, available in the same area of the Sonos App.

Anyhow, here is a Sonos support document that outlines the features of ‘wired’ SonosNet and ‘wireless’ modes that can be used by a Sonos System/Household.

https://support.sonos.com/s/article/3235

Hope that assists you with the understanding of your Sonos System.

Ok thanks I understand weird thing is tho I didn’t connect them via cable to the router but when I set the new system up after a reset it finds them connects them to Sonos net then try’s to connect to my internet then says may have to switch on then off to find . Well I’ve done all that and they’re nowhere to be seen and since trying to set the new play ones up I’ve now lost a beam sub and 2 play ones from my app (even tho they work through the tv as normal , I just can’t play music through them as they have disappeared I’ve never had them just disappear from the app before like this I also have a roam and that gone now also 

If you are using an iPad/iPhone I sometimes see them get bent out of shape and do illogical things. Force closing the controller usually helps. Occasionally, I need to uninstall the controller and fetch a fresh copy from the website. This is not disruptive because all important details are stored in the players.

Are the ‘missing’ Sonos devices listed in the Sonos App ‘Settings/System/About My System’ and do they each have IP addresses allocated to them?