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I hope someone can help me sort this out as I am going crazy trying to find the problem! I have a CCTV system (8-channel KGuard DVR rigged up to 8 cameras and connected to a BT HomeHub3 router, on fast BT Infinity broadband). The CCTV system itself is working fine, providing a live feed to a pair of monitors and recording all 8 channels to the DVR, but I am having trouble with the network connection. I have set everything up with port forwarding using the default ports as recommended in the DVR manual (ports 80 and 9000), and I have also set up DynDNS. If I open Internet Explorer and type my DVR's local IP address, then I can view the output of my 8 cameras absolutely fine. It also works fine if I type my public IP, provided I do this from a computer within my local network. And the DynDNS is working, because it also works fine if I type the DynDNS alias, but again only if I am on a computer inside my local network. If try to access it across the internet from outside my local network (either by typing the public IP or the DynDNS alias) then the browser just times out -- nothing comes up, not even a logo (IE says "This page can't be displayed" and if I try from Firefox it says "The connection has timed out"). What is the problem? Checking with canyouseeme.org shows my ports 80 and 9000 are open. In my router settings, I have placed the DVR into the DMZ, to rule out firewall issues, but this has not helped. The DVR itself appears to be able to access the internet, as it successfully keeps the DynDNS up to date and also corrects its internal clock using an internet time server. What am I missing here?! Thanks in advance for anyone's assistance!

Thanks. I am aware some ISPs block port 80 but canyouseeme.org shows my port 80 is open. I don't think this would be the case if my ISP blocked it, would it?

ok, thanks. that makes sense... i just don't know what settings are blocking it. looking forward to your further advice. no rush.

Thanks, both! Yes, the internal IP is static, and port forwarding associated with the correct IP. I don't see any such settings, except for the firewall and DMZ. I put my DVR in the DMZ and also briefly tried turning off the firewall, but to no avail. What settings should I be looking for? What I don't understand is this: everything works fine if, using a computer on my local network, I type the DNS alias into IE. This means that the DynDNS must be working (DNS alias gets translated into the correct public IP) and then the port forwarding must be working at least partially (the request is directed to the correct internal IP of the DVR). Why then is my DVR not responding to non-local requests?