@MerryGoRound 

Hi,

I can't test this for you, but I think the WISP Mode (also called Hotspot Mode) might work for you.

In this mode the TL-WR802N basically acts like a router, with the difference that the "WAN" connection is not via a cable, but instead wirelessly, hence keeping the Ethernet port available as a LAN port.

Since you don't need the router to connect to another network that provides Internet you just ignore the section "SSID(to be bridged) / MAC Address(to be bridged)".

  @woozle 

Thanks for the suggestion
I considered this solution before but was not keen on setting up connection to another network but gave it another go.
You are of course right, it does work very well, the drawback is that the "WAN WiFi" is not available in our use case (in the field where the portable router is used).
It still works, but without the "WAN WiFi", the router is never "ready”, and performance is quite sluggish and connection success is hit-and-miss, with long periods where nothing happens, and sometimes no connection at all. (not even to the tplinkwifi.net setup page)
By setting up another TL-WR802N in router mode, to supply a dummy "WAN WiFi", performance, what I have seen so far, seems as good as when using a router with working LAN.
A bit silly though, needing two routers to perform the task that one should handle ;-)