One further thought. Normally a router has a DHCP server. this is the component that hands out ip addresses to connected devices (unless you have configured all your devices with static ip addresses). Since Access Points normally operate in conjunction with a router it is possible that they are not configured to run a DHCP Server by default, although it may be possible to change this via the Access Point's configuration pages. If the devices cannot get an ip address they will not connect. However, if you have three Access Points connected to the same ethernet, presumably only one of them should run a DHCP Server !
John