ports not opening

Hi all can anyone please help I am trying to open ports 80 and 4524 on my Hub 3 to connect to my cctv dvr, when checking on port checker they are showing both closed, I have tried to setup port forwarding in the router but it keeps saying The rule already exists but I can't see it anywhere also I can't connect to it on the LAN. I access the cctv on an app called Ipolis mobile all worked fine till a few day ago when i had to change the DVR from a samsung srd to a slightly older one I have been over and over the settings in the dvr and all seems ok it is also pinging ok hope this all makes sense many thanks

Byron Jones