Since Cisco requires a valid for most firmware:

If your AP is already in autonomous mode (standalone):

: Setting up a small office network without a dedicated controller. How to Download To obtain this specific file legally, you should: Navigate to the Cisco Software Central Search for "Aironet 1600 Series" "Autonomous AP IOS Software" Look for release

else: print("\n✗ Download failed. Check network connectivity and URL.") sys.exit(1)

Ensure you are not trying to install an ap3g1 image on an ap3g2 device; they are not compatible.

Ensure your AP's flash memory is clean. Use the /overwrite command to remove old images.