This solution seems weird to me. When you 'authorize' iTunes you are authorizing the use of your Paypal account for a payment of a purchase from the iTunes Store. See? So this seems a bit crazy that by authorizing your Paypal to iTunes you can suddenly use your iPad for Cubase control.
What you probably did was 'allow' your iPad to be used for a remote to your iTunes library. And here you would turn on iTunes, plug in your device and follow the path to sync the library to your device.
I can do this in my network - and sync up to the library, but only when iTunes is on. And note, that iTunes is NOT on my recording computer, ONLY BONJOUR, but that my recording computer is on the network. So basically here I am saying I am very sure I do not want iTunes to be running on my recording computer when I am recording. Which means I can only imagine the issues you might have recording while you have iTunes turned on. So....... Q: now that you have set the iPad to access the iTunes library, and here you think this has caused iC Pro to function, do you need to have iTunes turned on to have control of Cubase? If you don't, then I would think you have found some other fix. Do you have to turn iTunes on to use your Cubase?
Well, getting back to your original post, I think you said your recording computer was connected via Ethernet cable to your network router? Here, if you have created a home network that allows devices to communicate with your PC, then the iC Pro should work - if you have Bonjour installed. I just don't understand what you mean when you say 'authorize' and particularly via iTunes. In fact, I thought I was pretty clear that you DO NOT NEED TO INSTALL ITUNES to make use of the Bonjour connection software. Steinberg, is this incorrect?
Cubase 6.5 (6.5.4) and 5.5 (5.5.3),WaveLab Elements 7, Intel C2Q9550@2.83Ghz, WD Black Cavier 500G SATA HD (X3), Win7 64bit, 8G ram, Gigabyte X48-DS5 MB, Mackie 1640i (FireWire), M-Audio Keystation 61es controller via an M-Audio Midi-Sport 1X1, iC Pro remote app