Ditto. Same sounding issue. Long time supporter of Subsonic and largely fine, but every once in a while the same issue crops up, by which point I can't recall if there was one distinct solution - so try everything and seemingly no success. Then at some point, it finally works again?!

Basically one day it worked, then it didn't. Possibly IP address changed but have updated port forwarding. Also rebooted everything.
Works in browser from full name URL in local PC, but not other devices on local network.
Any tips (other than how to request support) much appreciated.
Thanks.