My first post had mention I had try it.
End of that link, it said use value 800 or A00, I had try both value. Check by test website, my TLS 1.2 still not enable. Firefox still warning me not secure.
Did you get success experience?
The administrator wants to override the default values for WINHTTP_OPTION_SECURE_PROTOCOLS to specify TLS 1.1 and TLS 1.2.
Take the value for TLS 1.1 (0x00000200) and the value for TLS 1.2 (0x00000800), then add them together in calculator (in programmer mode), and the resulting registry value would be 0x00000A00.