Lab Networking setup has connectivity issues I have not run across before. Any help is appreciated!

So, I was asked to install a simple lab setup for my company, on an isolated ISP connection, for an experiment. We had to mimic a client's setup, so my choice of hardware was forced (and overkill for the job). Let me go over the topology and the problem.

The Topology

Switch - Cisco SGE2000P 24-Port Gigabit Switch. One port going to my ISP connection (just a wall jack on the lab end), one port going to the WLC, One Port to the Laptop I'm using to configure everything

WLC - Cisco 3504 Wireless Controller. Running everything through the Untagged Management VLAN (I know, not ideal, but this is just a lab setup). Port 1 to the Switch. Port 3 (PoE) connected to a Direct AP. WLC is also running the DHCP server, all addresses on the 192.168.1.X network.

AP - Cisco Aironet 1652-E Outdoor Access Point (god knows why we are using this). Has a static IP on the management subnet outside of the DHCP range.

Wireless Clients (only about 20 max will be connected). All are obtaining IP's and DNS servers through DHCP without issue.

DNS Server - Using Google's for testing (8.8.8.8)

The Problem

So, after many struggles (most surprisingly resolved when I disabled and then reenabled the license), I was able to get the AP to join. My SSID for my WLAN is broadcasting fine, Wireless clients can join and pull IPs, and Broadcast forwarding is enabled on the WLC.

However, Wireless clients are only able to load certain sites, intermittently. For example, one client was able to load Yahoo, but not BBC. 10 minutes later, it's the opposite. At first I thought it was wireless interference from other AP's, but that seems not to be the case, and when the sites fail to load, it looks like DNS failure (502 Bad Gateway).

This is frustrating as it happens without warning, then goes away just as quickly. I have tried using alternate DNS servers (tried Open DNS, Google's Backups, etc...), but it has not resolved the issue. Using an internal DNS server is not really an option. Does anyone have any ideas what may be causing this behavior?