Our Chromebooks were unable to connect to the internet through our IAP-105 access points for about a week, but our Windows, Apple, and Android devices all connected okay. The problem appears that we had accidentally created a duplicate SSID in our Chrome Management Counsole, one called PNet and one Pnet (the "N" was uppercase in one), otherwise both network entries had the same (correct) password, both were set to "preferred" and both set to "auto-connect."
Removing one of the two networks appears to have fixed our problem.
I'm wondering if anyone else has encountered a similar situation (or is interested in experimenting!); in particular our Google tech was windering if the different case "N" SSID would have affected connectivity.