Most problems are due to improper setup on the router. Setting a fixed internal ip address for the server and proper port forwarding rules on the router are essential for long term stability.
Never use port 80 or 443 - ISP's often use or block them and these are also the default ports on WHS for the remote login page. 8080,8081, work fine. 808X always works. I've seen others use different port numbers that have caused install failures.
READ:
http://monroeworld.com/android/subsonic/ This is the Windows tutorial but most of the concepts apply to any setup. Specific setup instructions for other Operating Systems are available in the Tutorials section.
http://forum.subsonic.org/forum/viewforum.php?f=6 and on the Subsonic website at
http://www.subsonic.org/pages/installation.jsp
In Subsonic Settings/Network - UNCHECK " Automatically configure your router to allow incoming connections to Subsonic (using UPnP or NAT-PMP port forwarding)." make sure to hit the SAVE button, you may have to scroll down to see it depending on your screen size. UPnP or Plug & Pray works sometimes, but not very often and you're better off learning what's going on anyway. You're dipping your toe into the network mgmt. thing anyway, might as well learn what's going on as home networks don't get simpler as time goes on. As your network gets more complex, you're going to have to learn this stuff! No time like the present.
Manually assign a fixed intenal IP and static route to your server at the upper end of the address range of the router, out of the way of DHCP, e.g. 192.168.1.254
Set up your router manually. uPNP might work, but most often it doesn't. Learing how to do it will be a skill you'll love having as your network grows.
Check the Subsonic Control Panel to make sure it's using the right port you're going to use. I typically use 8080 - 440, 8081 - 441, etc.
Set up port forwarding in your router to direct traffic on the selected port to your server. Consult your router documentation to do this, they are all a bit different.
Learn your external IP address assigned by your ISP. Go to
http://www.canyouseeme.org/ enter your SS port number and click the Check box to be sure the Subsonic port is open.
Test your setup by entering your external IP:port# to see if it connects. e.g.
http://98.117.185.5:8084/ If it works, you're good to go.