Network Switch = No Music

[TheOldPresbyope]

The switch is blocking multicast DNS (mDNS) packets.

mDNS is the discovery protocol used to resolve .local domain. You will experience a lot of breakage without mDNS.

Thank Tim.

I'll do some research to find out if the switch can be configured to handle that.

This would suggest you have an active, e.g., managed, switch. Pretty fancy. 

What model of each of your networking gear do you have? Virgin Hubs, Netgear WiFi routers, and Cisco switches come in various flavors.

Regards,
Kent