As the API-README states, you can't change settings in the miner without privs enabled in the miner for your IP address.
You may have read access due to the settings, but not 'write' access. Read the W: part.
The default settings in the miner are up to whoever provided you with the firmware.
P.S. linking to an old out of date git isn't the best idea
See my sig. I wrote the API and the manual.