Allow Proxies
Supported on: Firefox 70 or later, Firefox 68.2 ESR or later
Registry
HKLM
Software\Policies\Mozilla\Firefox\Authentication\AllowProxies HKCU
Software\Policies\Mozilla\Firefox\Authentication\AllowProxies Options
NTLM boolean SPNEGO boolean Description
If this policy is disabled, SPNEGO and NTLM will not authenticate with proxy servers. If this policy is enabled (and the checkboxes are checked) or not configured, NTLM and SPNEGO will always authenticate with proxies.