I actually think that there is an easier way to do this. If you are running via Ethernet cable, then you can configure the Gli deivce as a wired “Dumb AP” using this Dumb AP How To. The Luci config is real easy. Start with a clean device and backup your default config.

The device will NOT work as a router if you take it out of this config. You would need to restore the above backup. It’s possible to use the switch to change between 2 configs, but that’s advanced functionality.