Are there other wireless networks in the area that could be conflicting/saturating the airwaves?
I have even known of locations that actively suppressed unregistered access points, although that's more likely in a University setting than a secondary school.
I assume you have the Classmate wirelessly connecting directly to the D-Link on the robot per the
Rev A setup instructions?
P.S.
When you hardwire the Driver Station directly to the cRIO do you plug directly into the cRIO Port 1 or are you connecting to the D-Link (which is then hardwired into cRIO port1)?