Success. Can see the internal and external hard drives.
Now the inevitable next question if that's ok?
Via the HDR box some of the files that I transferred using the interface native to the HDR box show with a disc and red cross and they cannot be played. Viewing those same files via the web interface does not show this icon or nay indication that there is anything wrong.
Before I start moving anything about between internal and external hard drives I just want to make sure that I do not do anything to make this situation worse.
I now cannot remember if I formatted the external hard drive with EXT2 or 3. There was a comment previously that EXT2 had been found not to work. If I had formatted with EXT2, would I be seeing anything in the web interface on the external hard drive?
Thanks again for your very helpful advise and quick replies.