Thinking outside the box:
>Please help. The original software is unusable for what I need it to.
You wrote:
http://blog.hsp.dk/d-link-dir-810l-login-bypass/
>It’s not the prettiest of routers, but it only costs 332 DKK with overnight shipping, which is $50 exactly by the current rate. It is advertised as an “AC router”, which should allow extremely high WiFi speeds, but I’m honestly pleased with it just having 2.4GHz/5GHz dualband “N” networks.
It is performing great right now, and I like all the toggles and switches inside the control panel. BUT I WANTED MORE.
But of course!
So: you paid 332DKK for a router with weak firmware, 10/100 ethernet ports, (not gigabyte), and pretty weak open source firmware support (because the of the ralink chip in it--there's more available for broadcom/intel, etc.)--may I recommend you cut your losses here? Return the 810L for a 332DKK refund, and get something else?
One possibility: repurposing an old PC, and using MonoWall or Gargoyle?
https://en.wikipedia.org/wiki/Gargoyle_(router_firmware)
https://en.wikipedia.org/wiki/M0n0wall
Or OpenBSD
http://www.amazon.com/The-Book-PF-No-Nonsense-Firewall/dp/159327274X
PfSense?
Hardware Selection
Unlike most common commercial firewalls offerings, the pfSense project is just the software portion of the firewall. This means you get to tailor the hardware you choose to meet your environment's specific needs. You can use the live CD or memstick to test out your hardware without installing to the hard drive, or install to a compact flash card for embedded systems.
With hardware you have the option of purchasing pre-installed systems from the the pfSense Store, to piece together your own solution using our hardware selection guide, or hardware from one of our trusted vendors.
>Please help. The original software is unusable for what I need it to.
Good Sir: I would recommend that if this hardware, the 810L, does not run the software you need, that you get different hardware.
Hope this helps!