Hi. What was the purpose of the reset?

Check your Sonos and Alexa accounts to see to which country (if any) they are registered.

As @John B has said. Your location is stored in multiple locations:

1/ Against each Sonos device - You will need to use the browser version https://alexa.amazon.com

2/ In your Sonos profile - At the bottom of www.sonos.com once you have logged in.

3/ In your Alexa Account - Alexa App>Settings>Alexa App Settings

Please ensure that these are all correct.  For future reference, it is not recommended to Factory Reset your Sonos devices as it removes all diagnostic information - unless advised to by Sonos support or an experienced forum user.

Thank you @John B and @UKMedia for your swift responses. I did a factory reset because it was flashing orange when I plugged it in in my new apartment and it was the only thing I could do to make it get online. 

I have checked location on Alexa App - confirmed it is correct in Netherlands - and sonos.com - confirmed it is in the Netherlands. But alexa.amazon.com browser version shows no address set, but when I change the address and click ‘save’, it disappears and shows that I still have no address set. I have tried this on 2 different computers now with the same result. 

Any ideas of what to try next? Thanks!

Is that under the Sonos One device settings?

Also, please try this page: https://www.amazon.nl/ap/signin?showRmrMe=1&openid.return_to=https%3A%2F%2Falexa.amazon.nl%2F&openid.identity=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.assoc_handle=amzn_dp_project_dee_nl&openid.mode=checkid_setup&openid.claimed_id=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0%2Fidentifier_select&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&

@UKMedia yes that is under Sonos One device settings: Settings → Device → Edit Device Location. It lets me enter the address but then it disappears and won't save and still shows ‘No Zip code set’

I haven’t seen that situation for a while - it used to happen when Sonos first rolled out Alexa support.  Can you power down your router and Sonos Ones for 30 secs and retry.

@UKMedia no change I’m afraid.. still showing the same issues

What device are you access the web browser on?

@UKMedia I’ve tried it from both my Lenovo Laptop and my Macbook Air with the same result. 

Very strange…  As a test can you connect one of the Sonos Ones to your router via an ethernet cable and retry?

Yep done, and it’s playing music no problem but still have ‘Alexa is not available in your country’ 

Are you logged into any other Amazon apps on your device with the Alexa App? If so, can you please log out and retry.

@UKMedia I’ve logged out of amazon app and amazon alexa app on my phone and logged back in and connected with the ethernet cable again but still tells me ‘not available in your country’. The issue is now even more strange after I unboxed my Beam after moving and the Alexa function is working just fine on that…!

In that case, I wonder if powering off your Sonos One's for 5 mins might work?