Sonos cannot see my iMac iTunes library.

have you any devices on static IP addresses, also have you tried:

Shut down and power off all on this list, then power on, in this order: Modem Router Wired ZonePlayers and ZoneBridges Wireless ZonePlayers and ZoneBridges NAS if you use one Everything else (computers, printers, etc.) Wait until the component is fully up before restarting the next on the list.

If he's already been to the Sonos forums he'll have tried that already!  Although I could find his posts on there.

I'd always be inclined to start the NAS before the Sonos as well, given there's a good chance the Sonos will be trying to read off the NAS.

Was that for my suggestion, or Mr. Hoy's?

I only suggested the issue with Ports as I had no end of issues when I first installed Kaspersky and when I changed my firewall/router, I had some more fun - but then I moved to having a switch plugged into the external network firewall/router, with everything plugged into the switch and that sorted most of the issues.

Mr Hoy's, the "shut everything down restart in this order" schpiel is the standard advice. This doesn't sound like an IP issue though, more like a MacOS problem. Never did ask what version he was using, 10.5 isn't supported any more.

No worries, good suggestion.

Always presume the person has not tried something.

Scene, I have mine setup this way as well, Cyrus also recommend using a switch into the router and then plugging the device into the switch.

I run my own DHCP server and do not use the router to do this, I then have total control over my devices. I am not saying the OP needs to do this.

I would also turn off all antivirus and firewall for a brief period and see if devices start to connect.

Fair point - sometimes it's the most obvious thing that causes the issue.

I'd onlyrecommend the last point after physically disconnecting the router from the internet - I've seen an unprotected PC get infected in less than a minute when connected up...

Yes, I have Cable - so I go cable modem -> firewall/router -> switch

And everything then hangs off the switch. I use the firewall/router as DHCP server, as I finds this simplified configuration. I have an old wifi router which I'm now using as a wifi switch - everything seems a lot more stable now...

An update to this saga.

First of all, thanks to all who have offered suggestions.

As I suspected the problem lies with the new router and not with Sonos or my iMac.

I signed up with Sky for their Fibre Optic unlimited broadband (cheaper than BT infinity).

Sky provided the new router and BT Openreach installed their own modem.

Having spent a considerable time searching various forums, I have found that there are problems with Sky routers in so far as they don't support port forwarding and limit home networking options.

The internet forums contain numerous common issues with these Sky routers, such as not being able to use a NAS, Sonos not being fully usable (accessing music libraries), not supporting network printers, unable to share files between computers etc.

To make matters worst, apparently Sky hard code the passwords in the routers firmware and will not give them out, so you cannot substitute the supplied router with one of your own.

I spent some time talking to Sky Fibre technical support and they cannot discuss this sort of problem. The same on Sky's online support forum and confirmed by numerous anecdotes.  

Some work arounds are suggested, including assigning static IP addresses, but this doesn't resolve some of the issues with these particular routers.

Another option is to disable the DCHP and wireless functions in the Sky router and introduce another router into the chain to provide these functions and the wired hub. Reducing the Sky router to being a modem only.

This last suggestion would on the face of it, seem to be a possible answer to my problem; however in the Fibre Broadband case the Sky router's modem function is by-passed and the BT Openreach modem provides that function. There are no examples of this arrangement on any forum I have come across.

The set-up would be....

BT modem - Sky Router - Own Router - Home network

....where my Own Router would perform DCHP services and run all the home network connections, wired and wirelessly, to my iMac, Sonos, NAS and other computers and devices (laptops, iPad, iPod's, internet radio etc.).

Can anyone confirm this would work?

I have no idea about this level of computer or networking knowledge.

Stuff like assigning static IP addresses is quite beyond me, so I'm not really confident about tinkering with various settings.

The other question is why are Sky's routers dogged by this restriction?

Any other router will allow full home networking, including those supplied by ISP's, but not those supplied by Sky (including their new Sky Hub).

Assuming you don't buy another router with the same sort of restrictions then yes, there are plenty of other people doing similar things for similar reasons.

Well that shouldn't be necessary unless you start getting IP address conflicts but certainly not everyone does it. Depending on the router it should be pretty straightforward.

Well that's not entirely the case, have a look on the Sonos forum and you'll find people that can't get the Virgin Superhub to work with Sonos and have had to do the same thing you're talking about (set the Virgin hub to modem only and supply their own router), BT's Homehubs were notorious for blocking Sonos traffic, although the HH3 is apparently ok and I'm not sure there was any work around for that.

Somewhere on the Sonos forum there's a thread about recommended routers, might be worth checking that out before making a purchase.