One thing I noticed every so often--on my desktop computer, not all of the Chromecast devices would show up all the time. I occasionally had incidents where my old Chromecast would not appear in the list and a couple of times over the past several months, where the CCA in the kitchen would not show up. There are also somewhat rare occasions either one would not show up on mobile, yet for the most part, they seemed to be there most if not all of the time. The old Chromecast (which I had connected to an HDMI input on the Oppo 105) was powered by plugging into the 105's USB port (rather than its own AC adapter), so it did not show up when the 105 was not powered up.
In the browser, I open Pandora, right-click anywhere on the page, choose "Cast...", and it pops open a window of places to cast to.
Today it seems to be cooperating.
All of the audio devices are shown there. My original Chromecast is currently offline (as I am moving it to another room), but I see that all of the audio-capable CCAs are showing up (the "Oppo 105" is the CCA I have connected via optical cable to the Oppo's DAC), plus the Google Home devices.
If I go to YouTube and do the same (right-click, "Cast..."), it shows me the CCAs plus the (now disconnected) Chromecast and the Nexus Player on the TV (which has Chromecast built in):
("All Rooms" is a group of the three CCAs--Kitchen, Living Room, Oppo 105.)
Yet when I click the "Cast" button on YouTube..
...I get this, only the video-capable CCs:
So somehow, the Cast feature built into Chrome somehow (and sometimes) knows which devices are capable of playing the content.
So after all this, I probably don't have much to offer, beyond my experience with device detection being a little more spotty in Chrome than on my mobile devices. The only other thing I can offer is that I have set up all of these using the Google Home app on my primary phone. (The original Chromecast used an earlier app that was a lot more fussy about setup, and eventually morphed into the Google Home app.)
I will know more in a few days, because I am converting my network over to an all-new WAP (wireless access point) and new router/switches/etc., and am going to consolidate everything back down to one SSID, meaning that I'll probably have to retrain all of the CCAs and Google Home pucks for the new wireless. For now, though, despite setting up everything on my 2.4GHz SSID on my old WAP, I can reach all of these devices no matter which WAP or SSID I am attached to (my old 2.4 and 5.0, plus the new one). It seems to be fussy only during setup in that regard.
For now, I do not have the newer CCAs mapped to any specific IP address (using static DHCP in the router). My desktop though is always assigned the same IP as are the laptop and my tablet. The two phones I use are still not assigned an IP. So the Google Home/CC/CCA system seems to accommodate dynamic IP addresses.
If I can think of anything else, I'll let you know.