nedski wrote

Anybody know how to turn off the DHCP on an EAP115 or should I be looking at something else?

EAPs are just access points. They don't have a DHCP server.

nedski wrote

ok thanks. So any ideas how I make the AP a "dumb" AP so that it works in conjunction with my router, such that my connected devices simply switch between the two?

EAPs are already so-called »dumb« APs. Unlinke WiFi routers, EAPs don't have any routing functions nor any other services typically found on a WLAN router. It's the other way around: WLAN routers are just routers which also have a »dumb« WiFi AP built in (beside DHCP server, DNS server, a firewall and an Ethernet switch; often also a cable modem or DSL modem and sometimes even a telephony system).

To have wireless roaming between a router's WLAN and an EAP you just need to assign the EAP the same WLAN name (SSID) as being used by your wireless router's AP. To reach the EAP for management you should set it to a free (otherwise unused) IP from the router's local network IP. For example, if the router uses IP 192.168.1.1, set the EAP to 192.168.1.2 if – and only if – this IP isn't used by another device.

Then connect the EAP to the router's LAN. Clients connecting to the EAP will receive a dynamically assigned IP (192.168.1.whatever) as well as the gateway IP (192.168.1.1) and the DNS server's/forwarder's IP (almost always the same IP 192.168.1.1 in home networks) from the DHCP server running on the router. Check this settings on a client device connected to the EAP.

This is the basic topology (with or without an additional Ethernet switch):

forrest wrote

By the way, even you set the same SSID on the router and EAP, the client devices will not roam from EAP network to the router, they will disconnect from the router and then connect to the EAP automatically.

Client devices will indeed roam from a router WLAN to an EAP WLAN or vice versa if both APs have the same ESSID. Roaming (technical term: »Handoffs«) were already supported under the preexisting 802.11 standards. »Fast handoffs« aka »fast roaming« aka »seamless roaming« also requires a disconnect from one WLAN and a re-connect to another WLAN with the only exceptions that the client does not need to do a WLAN survey before connecting to another AP inside the same extended service set and that an AP can force the client to perform a handoff.

But »slow« handoffs as defined in 802.11 is still roaming. That alone is needed for the definition of an Extended Service Set (ESS) and the ESSID (most often just called SSID).