They won't join together in a Music Group so I can play music through them simultaneously
Amazon are suggesting;
If you have a firewall on your network, these UDP ports need to be open for the device to successfully connect to your network:
TCP PORTS 55442 55443 UDP PORT 55444
Kindly open the specified ports on the router. Refer the customer to the router manufacturer or the person / company who set up their Wi-Fi network for more information on opening the ports on their router.
Disable any Client Isolation on the router (i.e., Device Isolation, AP Isolation, Access Isolation, or Wireless Isolation).
If the network configuration uses multiple access points, range extenders, or a mesh network, have them run them in "bridge" or "access point" mode and disable any AP Isolation or firewalls set on the child access point.