KARTRACER wrote

The unit doesn't allow the WAN to be set on the same subnet as the LAN, which I have been able to do with other routers.

No idea what you mean with "allow WAN to be set to same subnet as the LAN". The TL-WR802N has only one wired port, which can be either WAN or LAN.

To use it as a LAN port and bridge the WiFi network to the LAN, so that it works as a wireless AP for the LAN, see page 93 of the User's Guide "Configuration for Access Point Mode".

KARTRACER wrote

Also, for some reason, the http://tplinkwifi.net address does not work. It did at one time, but doesn't anymore, even after a factory reset. So I must type in the IP address.

There are two reasons not to use a configuration domain such as tplinkwifi.net, but to use IP addresses for setting up APs.

First reason is cause of your problem not to be able to access the AP anymore after setting AP mode: the config domain needs Internet access. When converting from router mode (with Ethernet port as a WAN interface) to AP mode (with port as a LAN interface) you will lose Internet connectivity even if a cable is plugged in. The AP needs to provide IP addresses through DHCP and to be able to do so it already must have a static IP set, which now is assigned to the Ethernet port.

So I would reset to factory default, then note the static LAN IP address, change mode, set the PC to a static IP in the same subnet, connect the PC to the TL-WR802N by cable, get into the web UI and finish the setup.

For the second reason why I don't use configuration domains at all (just if you are curious), see http://forum.tp-link.com/showthread.php?91447-Once-again-cannot-access-Archer-C9-router-and-quot-tp-linklogin-quot-does-not-work-at-all&p=189922#post189922