One more strange blocking: trying to setup Ghostery (I use the Firefox extension), the extension says, while I try to connect it, "We encounter a problem".
Access to their website ( https://www.ghostery.com/ ) give this error (it's not a blocked page): "Secure Connection Failed"
If I untick "Tracking protection", all works well.
Silly behaviour: Ghostery is a do-not-track-me extension !
(and BTW: there's a tracker on this page, Adobe Dynamic Tag Management !)