1-Router port forwarding 80, 8080 through 8090
Recommended settings is to port forward those ports to the DVR and its also to recommended to put a static internal IP on the DVR just in case.
always pay attention to the Router Remote Management Port (can't be 80,8080-8090)
in some scenarios using DMZ as a final resort "not recommended"
2-Software Firewall on the DVR
Kodicom software automatically adds the exceptions in the firewall settings, you only need to allow the H T T P port.
3-ISP Port blockage "Which has always been tricky part"
Always Google your ISP for Blocked ports. if thats the case then few steps has to be taken to work around that.
I have gotten WebDVR to work on at least 200 DVRs all around the 50 States on all kinds of different ISPs.
Let me know if this is your case, so I can better help you.
Zach