@ejseibert To help us troubleshoot, can you do one more test?
1. Log on the management interface, go to the Parental Control page.
2. Click the “Disable” button at the top of the page.
3. Try to “Unlock Purchased Books.”
Do you still see “You must have an internet connection to use this feature.”?
Please note that there are two ways to turn of Parental Control: turn off for a profile, and turn off completely for the router. I just want to see if the problem is related to Parental Control.