From what I am thinking you are wanting to connect to the cctv webpage from outside your internal network?
If so you would need to connect through your browser something like: http://wan
Inside you local network (assuming on the same subnet etc) http://192.168.1.121:99
would work are you are on the inside so the port is not being blocked.
Port 99 is not a normal "web" port like 80, 8080, 443 so it could be possible that if you are trying to connect from outside your wan port 99 is being blocked?