Some router don't like ipv6 qos

While in a hotel in Japan, I could not connect using IPv6 to my server. The ping worked, and most strangely, using nc <ip> -6 22 worked too. I connected using IPv4 and looked if I would see any packet when trying to SSH, but no, nothing to be seen, no SYN. I was puzzled and fired up Wireshark on my laptop to see what was the difference between the packets leaving my computer. The difference was…