Have you tried to port forward or open up the port you need on the 4500? Not sure if it's open or closed by default. Also might check the firewall settings on the router too. Mine are set for UDP/TCP Endpoint for both.
As for this router being lame I know there are people that will say this router isn't the best. And maybe they have some right to say that. I for one along with some others I know, this router is really good and like some of the features. Ya, the FW on the main web site isn't good right now and presume DLink is working hard to fix that version. If your doing fine with what you have, Rule, If it works, don't fix it. Ask questions and do research on here.
I'm using A1 hw with v1.21 Beta 03 using Wireless N mode only and Gigbit Lan and gaming and Gamefuel enabled. Enjoying what it offers. Just as long as the FW dones't get worse. LOL. Shouldn't. Alot of times it might seem likes it's the FW thats faulty and in some cases, true. However a lot of issues seems to crop up in configuration of the 4500 and all the stuff it has. Always start with defaults and see how it goes, if you need more features enabled, start one at a time to enable them and make sure your configuring them properly. Once it's tested good for you, save off the configuration file of the router so you go back and reload it if something doesn't work.
We've all have some problems with most things. Why this forum is here, let us know what your problems are and lets see if we can resolve them. I think you'll like the router.