Try this while connected to the Access Server:
ping 8.8.8.8
If that works and you see a response, try this:
ping
www.google.com
If that produces an error, you should adjust your DNS settings on the Access Server. A common fix is to go to the Access Server's Admin UI and going to 'VPN Settings'. At the bottom there are settings to push a DNS server to the VPN client. Set it to push specific DNS servers, and push the DNS server 8.8.8.8, this is a public DNS server. Then try again.