Have you assigned reserved IP addresses to all devices in your router’s DHCP table? This smells a lot like a duplicate IP address issue. 

Hey Bruce,

Thx for getting back to so quickly. 

I haven't done that for one simple reason I don't know how to.

Any links for dummies would be appreciated. 

It's something I've never had to do before so any help would be appreciated.

Take care.

Check the manual for your router, each manufacturer seems to handle it slightly differently. 

A quick, non-permanent test would be to power down all devices that currently on your network (for now, the Denon and all Sonos should suffice). While they are unplugged, reboot your router. Give the router a couple of minutes to reload everything in a fresh ‘state’, then plug back in your Sonos, and Denon. 

The key to that process is all devices that will eventually carry audio needs to be powered down when you reboot the router, so that they will ultimately get new IP addresses when they’re powered back on. 

Cheers Bruce.

Trying it now. 

Will keep u posted.

Maxie

Same scenario m8.

Starts then cuts out. It's a connection problem I know. The sonos device is in the list of attached devices under IPv4 addresses.

Cheers.

Ok, at the least, we’ve removed the concept of duplicate IP addresses. I think at this point, it would be to your advantage to submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

Hey m8. I called Sonos yesterday.

All sorts of tests done and they said it's a network problem. Want me to call Sky and get them to change DNS settings on the router.

Good luck with that. Sky couldn't run a bath.

Listen,  thx for your time m8. I really appreciate it.

Take care eh?

Maxie

We cannot rule out hardware failure. SONOS Support has tools to assess this, we don’t have access to these tools here.

Hey Buzz. 

Thx for the reply m8.

Sonos did all sorts of tests and diagnostic tests. All were ok. They seem to think it's defo networking problem.

Who am I to disagree..lol

Will call Sky when I get a moment.

Thx for the reply m8.

Take care.

Maxie

If it is an ISP DNS issue it is usually no big deal to run your own local DNS or to connect to an external one like Google, Open DNS or CloudFlare that offer free ones.

Thx Stanley.

If u have a blow by blow account how to do that I'd be delighted.

Take care.

Maxie

Connected to Cloudfare DNS. Same problem. I'm totally stumped and tearing my hair out. Well , whatever hair I have left. 

Thx again m8

Take care.

Maxie