Hello all.

First, a quick system and network summary: I have four discrete networks; 2.4GHz wireless, 5GHz wireless, wired Powerline and Sonos Mesh via a Sonos Boost all going into a single router.  All software and systems up to date with latest versions and firmware.

Everything works fine and all devices can see each other across the networks EXCEPT Spotify Connect. 

If my Apple or Android mobile device is connected to the 5GHz network all Sonos products disappear from Spotify Connects's device list.  Move my Apple or Android mobile devices to the 2.4GHz network and all Sonos products appear in the Spotify Connect device list.

My Windows 10 PC connected to the network via Ethernet and a Powerline plug to the same router sees all devices (even my PS4)!

So...  Several scenarios prove my networks are open and communicating:

My Sonos mobile app doesn't care which wireless network I'm on and connects to my Sonos mesh and all speakers just fine.  Same with my sonos app on my wired PC.

Any mobile device using Spotify Connect on the 2.4Ghz network can see the Sonos mesh and all Sonos speakers in its device list.

My Amazon Alexa devices can see and control a wide range of home networking products (including my Sonos speakers via the Sonos mesh) regardless of their network connection.

My question is:  Why can't my Spotify Connect see my Sonos speakers or PS4 when my mobile devices are connected to the 5GHz network?  What's happening in the Spotify app to block these connections?

Thanks in advance for any insight!