Sonos 5.4 and Subsonic 5.2.1 on FreeNAS 9.3

Hello, first time poster. I've searched the forums and can't seem to find an answer. First, I discovered Subsonic last night and it looks like a great product. I've signed up for 2 years as a premium member. I installed the latest plugin on my FreeNAS 9.3 box, which is Subsonic version 5.2.1. I am able to connect to the web interface, add media, and play music over my laptop and other PCs on the local network. I've checked the box for the Sonos section so that it should be visible to my Sonos (version 5.4) on the local network.
However, my Sonos does not detect the service. I've tried rebooting both FreeNAS and Sonos, reinstalled the plugin, and tried toggling the service from within Subsonic. I've also tried checking the box to view local media servers (Windows and UPnP). Unfortunately, no luck. I've seen some other posters mentioning that Sonos v. 5.4 broke their system, but I haven't been clear on what (if any) fix is available. I look forward to your collective expertise!
However, my Sonos does not detect the service. I've tried rebooting both FreeNAS and Sonos, reinstalled the plugin, and tried toggling the service from within Subsonic. I've also tried checking the box to view local media servers (Windows and UPnP). Unfortunately, no luck. I've seen some other posters mentioning that Sonos v. 5.4 broke their system, but I haven't been clear on what (if any) fix is available. I look forward to your collective expertise!