I had exact same problem after getting a new router, had to remove Sonos from Google home, then Home could not reconnect to Sonos.  After a week of checking constantly and rebooting everything multiple times, I remembered I had added a private DNS to my android phone to block adverts.  I turned this off and voila immediately connected to Sonos and now it’s working again.  Too scared to turn private DNS back on though

Everything is working now. Enabling Google Assistant and/or Amazon Alexa, adding devices to Google Home via the Sonos skill, and enabling  the Sonos Skill on Amazon Alexa to discover all Sonos speaker. Thanks Sonos Team!

This still didn't work for me, but something else did. Coincidentally GA stopped working last week when adding Era’s to the system. Couldn’t figure out why. My hypothesis is that adding Era changed my sonos from 2.4 to 5ghz wifi.

What fixed it. Home assistant device used to set GA (phone) and Sonos should use the same wifi. My Sonos had in settings/network both 2.4ghz & 5ghz wifi assigned. When I removed 5ghz wifi from Sonos, and connected my phone to 2.4ghz, setup worked and was no longer giving “something went wrong” error.

Similar thread on google forums https://support.google.com/assistant/thread/311078906/google-can%E2%80%99t-make-a-connection-with-sonos?hl=en

Now its not working anymore. It worked for a couple of hours.

Same here ! 

Hi ​@Kazamaza et al

We now consider this issue to have been resolved with yesterday’s update. If you still encounter issues, please ensure your Sonos system and app are up-to-date, and if the issues persists, 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.

I can confirm it works again, thx!