I have a Lexmark E250d printer attached to a Thecus N2100 NAS.
On Windows Vista I've managed to configure this using an "Internet" printer port with the URL of http://thecus:631/printers/usb-printer. I can add a printer in a similar way in Windows 7, but it never manages to print the test page.
If I go to "Configure Port" in Vista, it just has "Security Options" - on Windows 7 it's asking about Raw mode vs LPR mode etc.
On Vista I'm using an E250d-specific driver from Lexmark; on Windows 7 there's a Microsoft E250d driver, or a Universal PCL XL driver from Lexmark... I wouldn't expect this different to be related to the problem, but I thought I'd mention it anyway. (Lexmark doesn't have a Windows 7 E250d-specific driver as far as I can see.)
Any suggestions? I was thinking of upgrading my main laptop from Vista to Windows 7, but I'd really like to get this sorted first...
EDIT: If I connect to http://thecus:631/printers/usb-printer via Chrome while capturing with Wireshark, I get this response:
HTTP/1.1 200 OK
Date: Wed, 06 Jan 2010 16:47:23 GMT
No idea what that's meant to be doing...
EDIT: On further consultation, this would appear to be the Internet Printing Protocol which is layered on HTTP. Printing a test page successfully from Vista posts to that URL. Will attempt the same on Windows 7...