Actually, 255.255.255.0 is the correct subnet mask for 192.168.254.2.
And 254 in the 3rd octant means it is a non-routable address, this is a good thing, it means that the address won't advertise itself to the world.
Although my nvr is set to 192.168.1.x, all my cameras are 192.168.254.x with...