Well since I installed the lastest FW version for my region, the router has been working very well for me and others. I see all of my connected clients and I an reserve IP addresses. We do know of the reservation IP address problem when devices are not connected that theres no way to un-reserve the address with out the device being connected. D-Link is aware of that. I assure you that D-Link does test there products.
How did you apply the FW update? You need to follow this to be sure the FW is applied correctly using IE or FF only:
FW Update ProcessEach region of D-Link handles there own FW and product support. It's possible that the version you have differs from other regions.
You could try loading FW from this region and see if the router works any better:
http://dlinkmea.com/site/index.php/site/productDetails/789Internet Service Provider and Modem Configurations- What ISP Service do you have? Cable or DSL?
- What ISP Modem Mfr. and model # do you have?
- Check cable between Modem and Router, swap out to be sure. Link> Cat6 is recommended.
- Check ISP MTU requirements, Cable is usually 1500, DSL is around 1492 down to 1472. Call the ISP and ask. Link>Checking MTU Values
When reserving IP addresses ON the router, I recommend powering OFF ALL devices, then turn on one or two devices at a time. Reserve each device ON the router and progress with adding more. I have about 20 devices on my network. Most of them are reserved. I have a printer, camera and NAS that are static IP addressed and out side the DHCP IP address pool. All works as expected for me.
IF this all fails for you then maybe it's just the unit that could be faulty and would need to be replaced. I recommend that you phone contact your regional D-Link support office and ask for help and information regarding this. We find that phone contact has better immediate results over using email.
Let us know how it goes please.