Some known ipv6 websites (including he.net) doesn't load

[thebas]

Hello, Trying to make progress on IPV6 certification, I can never pass the explorer level because the page can never identify I'm using IPV6.

I have set up a 6in4 tunnel on my mikrotik router, everything looks fine. I got an ip address on my desktop that was advertised by it.

I disabled IPV4 on network interface properties to make sure I was using IPV6.

I can access a lot of websites, like google search, gmail, youtube, whatsapp, wikipedia and some others. I can use microsoft teams, whatsapp application, microsoft outlook (can send and receive email), but some websites that I'm sure are IPV6 ready, like he.net and ipv6-test.com, does not work, the page keeps trying to load until they time out.

Does anybody knows how can I make it work, so I can finally pass the explorer level?

Thanks!

[tomkep]

Lower your MTU, start with 1280 (the minimum required by IPv6) and go up until it fails.

Please make sure to change it on BOTH ends of your tunnel.