I have two routers, one of which can only support DD-WRT, as a third party firmware (Buffalo WZR-1750HDP) the other of which can only support OpenWRT (TP-Link Archer c6 v3.2)- After much research and experimentation I have come to believe that my radius server should be on the OpenWRT router because OpenWRT wiki and forums are much more "open" about supporting Free Radius as a server, while DD-WRT seems a better candidate as a client to that server.
My wireless AP would be DD-WRT because I have read somewhere that it is wise to keep the wireless AP separate from the Radius server (that may or may not have been in an openwrt wiki or forum post. I think it was just general advice on the web).
My network is a home network and such that in part I merely want to experiment with FreeRADIUS, and the other part is that, if I could make it work, I would feel a lot more secure about my setup especially about those devices which can only connect via WPA2.
That is the extent of my thinking so far and I wondered if the asumptions I am making are correct