There was an Alexa outage over the weekend (we think, unrelated to Sonos) that caused some issues to Alexa running on Sonos devices.  Most users appear to have this resolved now but Disabling and then Enabling the Sonos skill may help.

On another point, factory resetting your Sonos devices would never resolve this type of issue and removes all diagnostic information - not recommended at all.

Thanks for your feedback. I’ve now also tried Google Assistant which is coming up with the same issue “couldn’t reach Sonos”. If it was related to an Alexa outage would that not effect other Alexa devices as well. These issues are specific only to my Sonos devices. 

It may do, the problem I have with testing this is that my Alexa devices are all working fine via Sonos.  But others who reported this problem, said it started to resolve itself towards the end of yesterday.  As you factory reset your products, can you check the Sonos App>Settings>Services & Voice>Amazon Alexa and ensure that each of your Alexa Sonos devices are shown as enabled?

Yes, they are enabled

Just a thought, can you please check one thing on each voice enabled device, using the command “Alexa, identify account.”. Can you confirm if the account is correct?  Did you disable and enable the Sonos skill?

Yes I can conform the account is correct and I disabled and enabled the Sonos skill,

Thanks

Okay, next thing to try is: Tips & Tricks - Resolving random issues impacting Sonos devices.. | Sonos Community