Have you tried setting that option through InControl?
My guess is that the error message is really saying - “I disabled configuration changes through the admin console because I am set to check InControl for all configurations” - i.e. lan access to write to admin website has been removed. Typically, with locally managed devices (no InControl), there is a security option for which interfaces have access to the administration website - it is an option choice with LAN, WAN, LAN and WAN. My assumption is that InControl wants to manage that option.
What is strange is that usually ALL of the options are hidden when InControl is managing a device – it is usually just a blank page that says - “Device configuration controlled by InControl”