Content server problems

When I log onto the content server running on Windows 7 on my local wireless network from my iPad 3 I am asked to authenticate twice.
Then when I have downloaded a book and imported it to iBooks, I use the back browser function to return to my list of books. Unfortunately, although it continues to show the number of books found, it fails to display the actual books, so no more can be downloaded. If I search again with either the same or different terms it continues to show the correct number of books, but fails to display them.
If I close the browser tab and go back in it still fails, but if I terminate the browser and return it works again - albeit with the same issues reported above.
If I chose the mobile browser interface, that works.

I believe this all used to work many moons ago, so is this a bug or have I failed to update some security setting?


Calibre 0.8.55
User name and password three alpha chars. Get warning that password might not be valid for some devices, but cannot find a password that is considered acceptable. Still get the warning with no password.
Local Windows task has no problem, but then does not open the PDF in browser.