Using RAVpower Filehub as router: how to?

This device can be used as a router, using one wi-fi point (e.g. the 2.4 GHz) as 'wan' connected to the main router of the network and creating a subnet which should be accessible on the other wi-fi point (e.g. the 5 GHz) .
With the LuCI interface I don't know how to make that. I cannot find a 'scan' button to scan for wifi on the existint network, like described in the Connect to client Wi-Fi network.
How do I do that ?

  • What model device?
  • What version of software?

(As I noted in a previous thread, noting the model and more details would help.)

It is the AC750 (2019 edition).
Software: the latest OpenWRT.

Let's try this:

  • Please provide a RAVpower model number - using the Wiki's syntax/terminology - name one the three supported devices listed on that page

Again, not very could be referring to 3 versions of OpenWrt...and one of those (snapshot) changes ~24 let's try this again too:

  • Please provide the exact version number (e.g. 19.07.3, 18.06.8 or SNAPSHOT).
  • If snapshot, please provide the revision number (e.g. "r11063-85e04e9f46")