One of the two web interfaces (GL or Luci) are still the best way to config things if you can, but if you need to do so, the command-line stuff is mainly done via the “uci” command interface, which edits everything under “/etc/config” using standard-formatted config files. The “wpa_cli” command is a more low-level command that I generally use for read-only stuff, like checking status and debugging. Another good command to check your actual connection is “wpa_cli status”.
The wireless stuff is in the file “/etc/config/wireless”. If you are making a “WISP” repeater connection, the relevant section is “wlan-sta” device (assuming an initial connection attempt has been made – otherwise, that section may not exist yet). Note that if you are doing a repeater connection like WISP, you can’t actually set the radio channel – that will be determined by the AP you are connecting to, so I always set it to “auto”.
I ended-up doing a rudimentary setup using the GL web interface as a bootstrap, and then edited the “/etc/config/wireless” file by hand to be what I wanted (2.4 vs. 5GHz radio, BSSID, etc). I should’ve mentioned that I have an ar750, which is dual-radio, and why 2.4 vs. 5GHz is relevant for me. If you do edit the file by hand in a text editor (as opposed to using “uci”), the WiFI config can be reloaded with the command “wifi reload”, or just reboot. If you want to see all the gory details of what can go into “/etc/config/wireless”: