NVG599 reserves IP address for 5.0 GHz / Wireless AC Radio, breaking normal DHCP useage

I have been fighting my NVG599 router to get the 5GHz / Wireless AC radio to work and it turns out I couldn't because the radio uses IP address #.#.#.64, which I had in my DHCP server range. Why in all that's holy would ARRIS (or AT&T) have it take up an address in the middle of the range so that we can't use the entire subnet IP block? Not to mention that I now have to change a bunch of device IPs that were previously set to static addresses on the traditional low end of the range.

Also, FYI, I never received a specific warning about the 5GHz radio until about the 5th time I had hard reset and reconfigured the router troubleshooting this problem, and probably only got that message because I only changed one setting at a time the final go through. I did receive a non-descript warning about an IP being used by the device, but it wasn't clear which one or for what purpose and I've never run across any router before that actually reserved one of the IPs for a wireless radio.

So I guess this post has two purposes: 1) I'd really like to understand why this was done because it's pretty inconvenient to only have IP addresses above #.#.#.64 to use and 2) Just in case anyone else runs into the same problem with a disable 5.0 GHz radio after changing the default DHCP settings, they can fix it without all the trouble I had figuring out what's going on.