People often confuse "IPv6" with "IPv6-only". And then state wrong statements. Pity.
But, hey, Let's try what you happens when you go IPV6-only. So let's turn off IPv4.
On Ubuntu, you can do it like this:
sudo nm-connection-editor
In there, go to your active Wifi network, then go to the tab IPv4 Settings. At Method, select "Disabled". Click Save.
To activate it, disable Wifi, and enable Wifi. And ... bingo ... IPv6-only!
Results:
Ubuntu works
Google, Microsoft and Facebook work
x.com results in a webpage with an error
A lot of Netherlands government sites work
KLM works, Transavia not
Smaller sites don't work
