After having upgraded the GL-AR150 with a later version of OpenWRT and the LuCI web interface, I wanted to see what resetting the device by pressing the reset button down for 10 seconds would do. Would it brick my device? Luckily no. However, you will find that it will no longer provide a wifi signal, and you will have to connect via the LAN port to configure it.
SSH Into The Device
Connect your computer to the device via an ethernet connection to the LAN port. Optionally connect the device to your network by plugging an ethernet cable from your router/modem/switch to the device's WAN port.
SSH into the device with
Update the Device And Install Web UI
Run the following commands to update the device and re-install the web UI which we will use to perform the rest of the configurations.
opkg update opkg install luci
Connect Browser and Set Passwords
Use your browser to connect to 192.168.1.1 and set a password for the web UI at the prompt.
Click the "Go to password configuration..." link in the yellow bar at the top to go to the password configuration page, and then set a password for accessing the device.
Go to the wireless settings menu.
Click the edit button.
Optional Step - Change Country
For non-Americans, click "Advanced Settings".
Change the country code to whatever is appropriate. For people in the United Kingdom, we are listed under GB - United Kingdom, so we don't appear in the list next to "US - United States" where it usually is when selecting countries in online forms.
Set Wifi Password
Now click the wireless security tab.
Change the dropdown menu from "No Encryption" to "WPA2-PSK" and enter a password into the "Key" field. This will be the password you enter when connecting to the wifi.
Click the blue "Save & Apply" button.
You will be redirected to the page shown below. Click the "Enable" button to turn on your wifi.
Optional - Change Channel
You may or may not wish to change the channel at this point. "Auto" is a good default if you're not sure. It is even better to use the wifi analyzer tool to manually see what's being used and try to set a channel that is free.
Optional - Set Transmit Power
It may also be a good idea to reduce the transmit power level if you are setting up single-room wifi hotspots in a shared office space, or at a cafe/shop. This is where you want the wifi to only travel a short distance. If everyone did this, then we wouldn't have wifi hell where there are no free channels.
You now have a working OpenWRT router.