Correctly flash OpenWrt firmware. Instructions and current firmware:
https://openwrt.org/toh/gl.inet/gl.inet_gl-mt300n_v2

Your status screen should look like this:

Your Network|Wireless screen should look like this:

When connecting to or editing connection settings, the option for PEAP should be in Interface Configuration|Wireless Security (at bottom of the page).
Remember to set the correct Authentication method (MS-CHAP in my case works fine, might not in your case)
3

And remember, Google and Wikis are your friend :slight_smile: