I, too, connect to Calibre wirelessly using my Kobo Touch.
To find the IP address of the computer with your Calibre collection (each computer in your house will have a separate IP address):
- from the start menu select "run" (on windows 7, typing "run" into the search box will find the "run" application for you)
- type
cmd and click on "ok"
- in the Dos window that pops open, type
ipconfig and hit "enter"
- Looking at my husband's XP computer, the IP address is listed beside "IP address". On my Windows 7 machine it's listed beside "IPv4 Address". You need to use this IP address, and not the one that says "Default Gateway".
Just open the Kobo web browser (I assume this also holds true for other ereaders) and into the address url enter what yhamm has stated:
http://youripaddress:8080
As long as Calibre is running on your computer, and you've remembered to start the content server, Kobo will see your library. I have my Calibre library set up as my home page on my Kobo web browser (and have my husband's also under favorites since we keep separate libraries on our separate computers.)