you must use
dst. address = the ip of interface you want reachable the dvr
protocol tcp
port = 80 ???
to address = dvr address
to port = 80 ???
YOU MUST SET ON WHICH PORT.
IF YOU NOT SET ON WHICH PORT, ALL THE INCOMING TCP TRAFFIC WILL BE REDIRECTED TO DVR.
the dvr can be also want one or two udp ports.
Check on config menu for a list of all ports needed.
on doubt open both tcp and udp.
Usually web = TCP 80
RTP / Media = 1750 UDP
Mobile = 19168 UDP