Hi @ian_16 

Welcome to the Sonos Community! And, apologies for the delay.

Sorry to hear of this issue you are having with adding a Play:3 to your system.

When a speaker has a flashing green light, the Sonos app should automatically detect it and offer to add it to your system. If this is not happening, I recommend a reboot of your router - please turn it off for at least 30 seconds. The router will take a few minutes to boot back up - while you are waiting, please restart your phone too.

Ensure that the Play:3 still has a flashing green light (if it has changed to Orange, unplug the speaker for a moment, then plug back in and wait for the flashing green light again) and open the Sonos app.

If it does not then offer to add the Play:3 to your system, I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.

I hope this helps.