windoes 10 proxy turned off automatically

windows 10 proxy setup changed mysteriously
windows 10 proxy settings doesn't stick

It turns out that Firefox will change it. To turn it off:
i. about:config in the address bar
ii. network.proxy.enable_wpad_over_dhcp needs to be FALSE

Solved: Windows 10 second monitor turn off after locking screen (no HDMI signal)

How to change Lock screen timeout before display turn off on Windows 10