When VPN is disabled, do you have another connection set up on the router? How do you connect it to the main router? Should set up a second connection according to your ISP.

Verify the VoIP settings with ISP. Contact tplink technical support if problem exists.

Was he able to open websites after he reached the time limit? Please note that the Time Limit counts the time when the device has data flow, if the phone is connected but no in use, that time will...

No, didn't have this problems when updating the firmware. It's better to update the Deco when you next to it.

What VPN apps does he use? Deco can block some VPN apps. hansremmerswaal wrote I also bought it primarily to manage my 13 years old son's internet usage... And guess what... Within days he found ways...

Good suggestions!