I noticed that you installed the EAP Controller to manage the EAP320. But if you only have one of them and don't need the advanced portal functions, you don't have to use the EAP Controller. The following shows how to configure EAP320 back to standalone mode.
1. Simply reset the EAP320 back to factory default settings.The EAP works independently as a standalone access point.
2. By entering the IP addressof the standalone EAP(192.168.0.254), you can log in to its web interface and perform configurations. Typically, a dsl router or router acts as the DHCP server.
3. Follow the steps below to log in to the web interface of a standalone EAP. A. Connect your wireless devices to the EAP by using the default SSID printed on the label ofthe EAP device. B. Launch a web browser, enter http://tplinkeap.net in the address bar and press the Enter key. C. Enter admin (all lowercase) for both username and password to login.

For your topology, where is your EAP Controller installed? If it's installed after 941HP, there is a NAT. You need to do port forwarding with EAP Discover Utility. Please see this FAQ: http://www.tp-link.com/en/faq-1363.html
ADSL 8968nd (192.168.1.1)
LAN1/WAN -->(192.168.1.Y) 941HP (192.168.0.1)
LAN2 --> EAP320 (192.168.1.X)
LAN3 --> NVR
LAN4 --> PRINTER


For your question, whats is DHCP fallback gateway?
When the device cannot get a dynamic IP address, the fallback IPaddress will be used by enabling the Fallback IP feature.

Normally, just leave it blank.