Solved! M1 Fail to connect to contents server

[jrain]

The short version
[No one else is currently complaining of Contents Server connection problems on an M1/Ventura. I'm posting a dusty solution for future fails!

"About:blank"
The Calibre server recommended address
http://192.168.178.96,port 8080, HTTP
fails to connect to the content server for three different eReaders.
M1 mbookPro OS 13.3.1
http://myMBPro,8080,mobile WORKS instead

Despairing and ready to expose myself to net humiliation,
for some reason I looked at the Calibre address saved on the old Sony.
It uses a short hand address and that has been working for years:
http://myMBPro,8080,mobile
ie just the device name and a port. I tried that and bingo, worked on all three readers.

Why? Is the mac translating the address differently?
or is the invocation of the "name" a free pass to TCP land?

I had wasted a couple of days checking everything syntax, ports, firewalls, ghost devices, Netstat stats.. Since the failure was the same on all my readers (Aura ONE, Elipsa, Sony prs T3), I presume the problem has something to do with the latest Ventura software?

Previous to the new M1 I was married to HighSierra on an old Intel Mac for music software reasons and Calibre never failed me there.
THANKS again Kovid!