I am trying to run Roon direct off a little Linux based computer and my external HD is attached to an Airport Extreme. I try try to type in the pathway (smb://10.0.1.4/Volumes/Music) and get an error message
Hmm. The first thing I would do is verify that everything is on the same sub-net. aka 192.168.0.x. Roon does not work across subnets.
However, I would just connect the external hard drive directly to the Roon Server. With Roon, when you initiate a song to be played, the music file is first sent to the server and then from the server to the DAC. This can add a lot of traffic and potential lag depending on your network; it is so much easier if the music is local to the Roon Server.