Adding websites to exceptions?

I have a customer who I set up Avast free for, and the network shield seems to block their surveillance camera’s webpage. When I disable it it starts working again. How would I go about adding an exception for this web address? Or would I need to base it on port number or something?

Go to:
Real Time Shields > Web Shield > Expert Settings > Exclusions (3rd one down)

First of all, I’d ask - is there anything reported by the shield (an infection, I mean)? If yes, what exactly?

I will double check this later today but nothing as far as I remember.