Here's a work around that hope helps you as it did me. Here's what I was trying to do. I wanted to reserve a static ip for my HikVision Network DVR and it seemed always return the host name as -- . My older DLinks would happily map a set IP with the devices MAC but this model seems to additionally expect a valid hostname.
Instead of reserving an IP from the DLink Router configuration, I set my DVR to use a static IP which was outside the router's DHCP range. I set mine to 192.168.0.250 and my router's DHCP range was 2~199. (Apparently you shouldn't set something within your DHCP range to avoid conflicts) And that's it !
Now, after every reboot, the same IP is assigned to my DVR and my port forwards work nicely too
