'wentel' wrote:
access for, lets say, half an hour accepting the terms

  • access for employees using a login account

My client does this by having two SSID's, one “private” for employees, and one “public” with 90 min per day.

With DD-WRT you can create a secondary SSID which you can password protect, so only those can access it who knows the password. Go to Wireless and click on Add under Virtual Interfaces. Then be sure to password protect that channel so only those can access it who have valid password. Click on Wireless Security and add choose a security mode (WPA2 Personal is recommended) with TKIP protection. Then choose a password for this channel.”