ну что далеко ходить, даже самое простое не работает:
# curl -v6
https://ipv6.google.com/* Trying 2a00:1450:4011:80b::1003...
* TCP_NODELAY set
* connect to 2a00:1450:4011:80b::1003 port 443 failed: Connection timed out
* Failed to connect to
ipv6.google.com port 443: Connection timed out
* Closing connection 0
curl: (7) Failed to connect to
ipv6.google.com port 443: Connection timed out