As per many and varied posts over the past few months, I had been completely unable to get Stanza or Megareader to "see" the Calibre server.
Knowing this, today I fired up a newly acquired mobile wifi device and was able to use the server without issue as I had on my normal landline based network. Disconnected it, and then checked how/whether it was working with my local network... and it is.
I don't know why, or how. I hadnt tried using it for ages... so whether it was one of the recent updates to Calibre, or whether using the mobile wifi gadget beat it into submission, I have NO idea, but I dont care, I have wifi Calibre access from Stanza and I am simply overjoyed!! FINALLY everything is as it ought to be.

: