Can you confirm which light pattern you are seeing:

https://support.sonos.com/en-gb/article/sonos-led-lights

Flashing green. 

Which Sonos App are you using (on which mobile device?) - does everything meet the Sonos system requirements mentioned in these two links below: 

• https://support.sonos.com/en-us/article/sonos-system-requirements
• https://support.sonos.com/en-us/article/sonos-app-requirements

Perhaps ensure the 2.4Ghz WiFi network is 802.11b/g/n compatible with (ideally) security mode WPA2 Personal and if the issues persist, see what happens when you temporarily wire the speaker to the router (if practicable).

Sonos beam Gen 2 phone is Samsung and S20 5g Ultra. The app is installed OK and but what do I need to have to tap to activate the final stage. Tapping the sonos at the flashing green does nothing. 

I’m sorry I don’t understand what you are referring to here? Can you kindly provide some further details. Perhaps include a screenshot of what you’re seeing.

Thanks for the responses and information,. Unfortunately at 90+ it's all a bit beyond me. I will have to seek local technical help to move forward. Thanks again all. 

Perhaps give Sonos Support Staff a call. See the below link to contact them:

https://support.sonos.com/s/contact

Yes I'll try that thanks. It's not really causing a problem apart from being unable to modify settings, the soundbar works. I had a Bose previously, much easier with a remote.