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Firefox Blocks 0.0.0.0 IP Addresses: Tell Us What This Means To You!
(connect.mozilla.org)
A place to discuss the news and latest developments on the open-source browser Firefox
Do you have standard Firefox with default options that does this? This has not been my experience.
You could try out with a new profile if it works out the same.
I just tried to use the Developer version. With no addons.