How to stop Firefox from making automatic connections

How to stop Firefox from making automatic connections

Preferences:
When Firefox starts	Select 'Show a blank page'
Update Add-ons Automatically	uncheck
Never check for updates	check
Automatically update search engines	uncheck
Provide search suggestions	uncheck
Query OCSP responder servers	uncheck
Firefox Data Collection and Use	uncheck
Delete all your Live Bookmarks

about:config
app.update.auto	false
extensions.blocklist.enabled	false
browser.safebrowsing.downloads.remote.enabled	false
network.prefetch-next	false
network.dns.disablePrefetch	true
network.http.speculative-parallel-limit	0
browser.aboutHomeSnippets.updateUrl	blank string
browser.search.geoip.url	blank string
browser.startup.homepage_override.mstone	ignore
extensions.getAddons.cache.enabled	false
media.gmp-gmpopenh264.enabled	false
browser.casting.enabled	false
network.captive-portal-service.enabled	false
Disabling WebRTC (https://browserleaks.com/webrtc)
media.peerconnection.enabled	false
media.navigator.enabled	false