I cant open ipv6.he.net via IPv6!

[mehrzadmo]

I'm newbie in ipv6 . I register an account in https://tunnelbroker.net/ and create a tunnel between my router(mikrotik router ) & the site .  and route a /48 prefix and config it on my LAN side . now I can ping any IPv6 on the net , I can browse IPv6 site like ipv6.google.com , youtube , facebook , ...
but
I cant open ipv6.he.net that I need for my second step certificate .
I try another browser , I disabled IPv4 on my computer but not working yet .
I can ping the URL , and site IPv6 address .

what can I do ?