I had some time to today to play around with it. And still can't figure it out. I have not added a password to limit one of the potential problems, once I know it is working, i'll deal with adding security.
Here's the various attempts I made to resolve the issue.
-I tried accessing http://mydns:port/DeviceDescription.xml
from the phone web browser with wifi off but it returned a 404 error, connected back to into my wifi, accessed page http://mydns:port/devicedescription.xml
and viewed the file with no problems.
-Disabled phone wifi, went to http://mydns:port/
and loaded the twonky browser with no problems, could view the various files through the browser.
-I have also tried turning auto detect back on, then changing the base url to the http://mydns:port
too. Once again, works while phone connected to my wifi, but once I shut off wifi on the phone, browse no longer works.
This is where it starts to get really weird, when using the base url...
I start plugplayer with the phone wifi on and being able to browse and access the server. I then select a song and plugplayer creates a playlist. I started playing the song and shut off the wifi on the phone. the song continued to play... went to plugplayer playlist and selected another song. That song started to play with no problems. I then selected browse, pressed back, to the parent folder. Selected a different folder, the status bar at the top looked like it was updating and nothing loaded. The bar eventually went solid grey and nothing was listed. It seems I can play songs that have already been loaded to the plugplayer playlist, but I am unable to browse the server to add to the existing playlist. I also created multiple plugplayer playlists from the same server. with the wifi off, I was able to switch between the various playlists.
Since I can access the the twonky browser from outside the network, not sure why I can not pull the devicedecription.xml file remote too. I've spent a lot of time looking up resources for this, but still haven't found a resolution. Thanks for your help.