I configured it! The trick was to set a static ip address on the PC I used. I just wonder why I didn't have to do this the first tim I configured it. It connected right away to tplinkeap.net but now...

I don't see a way to reset the EAP. There's a pinhole on the POE adapter, is that how it's done?

I did so once already wirelessly--connecting to TP-Link_2.4GHz_xxxxxxxx and loging in as admin. I changed the SSID, and login info. And everything worked. But for some reason, it seems to have now...