Dumb AP / Access Point Only
1. Disconnect the (soon-to-be) Dumb AP from your network, and connect your computer to it with an Ethernet cable. 2. Use the web interface to go to Network → Interfaces and select the LAN interface. 3. Enter an IP address “next to” your main router on the field “IPv4 address”. (If your main router has IP 192.168.1.1, enter 192.168.1.2). Set DNS and gateway to point into your main router to enable internet access for the dumb AP itself 4. Then scroll down and select the checkbox “Ignore interface: Disable DHCP for this interface.” 5. Click “IPv6 Settings” tab and set everything to “disabled”. 6. In the top menu go to System → Startup, and disable firewall, dnsmasq and odhcpd in the list of startup scripts. 7. Click the Save and Apply button. Hard-Restart your router if you're not able to connect anymore. 8. Go to http://192.168.1.2 (or whatever address you specified) and check if the settings for the LAN interface are the same. 9. Use an Ethernet to connect one of the LAN ports on your main router to one of the LAN/switch ports of your “new” dumb AP. (There's no need to connect the WAN port of the Dumb AP.) 10. You are done.
Would not it be batter to skip step 3. which is manually setting the IP address and DNS address, and allow Client dhcp odhcpd to continue to run. That way the router, or the admin of the router, could control the IP address and DNS address of the access point. That way, you can take your access point and plug it into an arbitrary network with DHCP and everything works. If the administrator of the router wants the access point to have a particular address and DNS address, he can use his standard dhcp server management tools to control it. I have had commercial access points and that is how it worked.