I recently began having this problem--perhaps a month or so ago--and cannot find any solution on any other thread.  Nothing on my network has changed as far as I know.  My pogo plug is plugged into a Linksys WRT 54g router.

When I am on the same network as my pogoplug, I can access everything just fine.  I can stream the movies, pictures, documents etc. that I have on the Western digital hard drive I have attached to the pogoplug.  I have one mac and one windows pc and they both play fine with the pogoplug so long as they are on the same local network.

When I am attempting to access those same files through a different network connection (at work/a friends home etc.), however, I have troubles.  At times I can browse through the drive and folders just fine, but when I try to open any file, the program will just time out (i.e. if I try to open a video file VLC player will just sit there trying to load but without any success.)  At other times I can see the root folder of my hard drive but when I try to open any other folder it just loads up and appears to be empty.  At no times am I able to successfully open any sort of file if I am not connected to the same local network as the pogoplug.  

Further, if while on a different network I try to copy any files onto the drive I am presented with a message reading, "The operation can’t be completed because an unexpected error occurred (error code -1407)."  (that is the error on my mac--the windows pc is a desktop and hence always connected to the local network.)

I'd greatly appreciate some help as I am about at my wit's end here.