When a technician is unable to connect to a laptop over a VPN, one of the most common reasons is that the firewall settings on either the laptop or the network are blocking the connection.
Wireless protocol: Unrelated, as the technician is already connected to the VPN.
DHCP pool: Unlikely to be the issue, as it deals with IP address assignment.
Content filtering: Typically involves filtering web content, not affecting direct connections.
Firewall: The correct setting to review, as it may block the necessary ports or services required for remote access.