hi
your DVR is set corectly ?
first set your DVR with default setings
second, check iour LAN IP classes Ex 192.168.1.X
your router must have LAN IP 192.168.1.1 or 192.168.1.254
set your DVR IP 192.168.1.10 (default), GW 192.168.1.1 or 192.168.1.254
same your router LAN IP
and SM 255.255.255.0