Thanks for updating the dataentry, however...
- Target ar71xx-ath79 was correct. Please change back to ar71xx-ath79
- GL-AR300M does not have any detachable antennas. Detachable antennas are only present at the "Ext" variant.
- "Firmware OpenWrt snapshot Install URL" is incomplete. Please provide the complete download links.
EDIT: Split off from the original topic since we were drifting off-topic.