Thank you for touching base with me @Eric_Peters and providing an update on your testing. Very appreciated!
Moving forward, based the information shared in my PM I do believe that the right course of action here is to start looking into your network configuration. When it comes to network troubleshooting we always suggest using the process of elimination to try and determine where things are failing. Making the network configuration as simple as possible, and then adding complexity back into the chain of communication one step at a time. As it stands currently (from your report) your network topology is as follows:
“Netgear 16 Port Gigabit Switch (2 pcs 8 port switches and one extra POE switch for security cam system). Wifi Network: Apple Airport Extreme (7.6.8) + 2x wired Airport Express.”
“Sonos ZP 80 Connected wireless to Wired Songs Play 1 (at least thats what I suspect). The songs play 1 is connected to the main switch Through another switch.”
I would recommend getting your core, NAS, and ZP80s all on single switch mounted directly to your router, first, with all other devices (temporarily) offline. In this configuration confirm how the ZP80s respond. From there, as mentioned, start to expand back out.
Lastly, I just wanted to point out that we have seen some issues in the past related to Apple’s line of networking devices (i.e Apple Airport Extreme (7.6.8) + 2x wired Airport Express), as mentioned in further detail here by our CTO Brian. Now I want to be clear that I am not saying that this is cause of the problem here, just merely sharing some feedback based on previous support issues 
Looking forward to hearing how your testing goes!
-Eric