Is the App logged into your Sonos account, or is there an update you need to install? See… ‘Settings/System/System Updates/Check for Updates’, or is your mobile device operating system perhaps only ‘partially supported’, as mentioned here on the Sonos App ‘Requirements’ support page:

https://support.sonos.com/s/article/4875

Nope it’s kind of a strange issue , my sonos beam and the surround were connected to different network and I changed the wifi network and I did a factory reset and tried to connect to new network , did try to connect one by one , one connects and the moment I try to connect beam the other one is vanished , it’s a strange thing, tried to speak with sonos customer care they were unable to fix it and now wants me to call them tomm to give them remote access , so that’s where it’s stuck 

When you connect the second one, are you just using Add Product? You aren't going through the whole setup process again?

Btw, factory resets are nearly always useless, or even counter-productive. 

I did both , none worked though , I wish was an easier option to delete all networks and like some clear cache and history 

You chose Xmas day to switch to a new network? That is some bold risk management right there.

Please tell us which router you switched to. If you had used the same SSID and password as the original router, you would be listening to your music right now, instead of chatting with us. Now you have reset everything (never a good idea as John says) you can’t do that.

Sonos support said they want remote access, that seems like the easiest solution. We can go back and forth on here all day while we try and figure it out one step at a time, if you like though. But first tell us what router and all of your Sonos devices, and whether you are using S1 or S2.