OK, so I entered the world of Sonos over the holiday period.
Everything got set up and going pretty easily.  I'm aiming to use a traditional CQC media repository (currently using an old JRiver license - shame that Plex can't be used as a repository, as I use it to feed everything else now) and then use the V2 Sonos Media Renderer driver.
All good so far - and up and running in no time.  The problem I have is that every 1-2 days the Sonos Media Renderer drops offline, and I find it in a state of 'Waiting for Comm resource'.  This happens for both the v1 and V2 driver, and reconfiguring the driver will not allow a connection.  Neither with restarting the CQC service or rebooting the CQC server.
When the Sonos Media Rendering is behaving like this, the Sonos Media Player *will* connect to the Sonos, and control it (I only did this for test purposes, as I'm not tintending to control the Sonos in this way - I want media browsing)
The only way to re-establish a connection with the Sonos is to power cycle the Sonos.
With logging on high, all I see in the logs repeated again and again is :
01/02 13:06:57-HTPC, CQCServer, CQCDrv_Sonos_Media_RendererThread8
{
    CQCKit, CQCDriver_DriverBase.cpp.3445, Status/App Status
    Driver 'Sonos_Media_Renderer' is trying to get its comm resource
}
I had some issues with this, and I ended up having to set Sonos up as a static IP address.  Since (from what I could tell) the app does not allow you to do this, I had to supply the Mac address in my router and force it to use one there.
For me, once it was setup, CQC did not have any issues with finding either of the Sonos drivers, and seems to stay connected.
Was the problem you saw related to changing IP addresses for the Sonos units? I've only had the Sonos up and running for a week, and the IP address as been constant since the initial install.
I'll fix the IP address in my router and see if it does help, but not sure why it would if it does ;-)
BTW, you can also hard wire the Sonos and disable the wireless on any given box, which is probably something worth doing for those near a network connection. That also makes them one less wireless attack vector I guess.
It doesnÔÇÖt feel like a network issue though, as the Sonos Media Player device driver connects to the Sonos, but the Sonos Media Renderer is stuck trying to connect.
WhatÔÇÖs different with the 2 drivers that would explain this?
Their app may use their new, simpler API, whereas our driver uses the UPnP interface. If it can't connect, then that's likely a UPnP level thing most likely. Though you should put the driver into verbose logging mode for a couple minutes then get a log dump and post it here to get a better feel for what is going on.
UPnP uses UDP packets, not TCP/IP, so it is affected by anything that would affect broadcast msgs in the network, such as network segmentation and such. Not sure what other network settings type things might also affect it.
Anyway, get a log dump before we start speculating.
Im not referring to their app, but the alternative CQC driver.  So, when the CQC Sonos Media Renderer gets into this state, the CQC Sonos Zone Player will still connect to it and control it.
Looking back through the logs, I think the attached log shows when something went wrong early today. I can not be sure though, as it was about 6 hrs later that i noticed the Sonos was no longer responding to control. 
I think the driver should have been in high verbosity when this occurred, as i switched it to high a couple of days ago.  Right now, of course, it is behaving - so nothing to show in the logs ...
01-02-2018, 03:58 PM (This post was last modified: 01-02-2018, 04:00 PM by Dean Roddey.)
It will only stay in high verbose for about 24 hours, to avoid the possibillity of accidentally leaving it that way. It should be fine to turn on logging once it gets into the state. We might miss some initial thing possibly, but most likely whatever happened is still happening and we'll see it as the driver tries to periodically reconnect.
The difference would mostly likely be that the media renderer accesses the media renderer UPnP classes more extensively, while the zone player one does so much less because it's just providing basic control.
Oh, BTW, make sure your Sonos firmware is up to date.
My issue was the DHCP IP address moving the Sonos around and no way to make it static within the Sonos App, and without a static IP address, it would have trouble finding it at times.  By assigning it a static address using the address reservation in my Netgear router, it started working.  I am thinking it was a UPnP issue in addition to the IP address moving around if anything was rebooted, but it seemed to make everything calm down for me once I made it static.
ok Dean, I have just discovered that the Sonos driver is in a disconnected state again. 
Attached is a dump of the log after I put the driver in high verbosity. This is identical to what I saw before, and gives me no clue as to what might have gone wrong.
