If your IPv6 address begins with fe80::
This type of IPv6 address is called link-local and is therefore specific to a network interface on your computer. You can use ifconfig to show information about the network interfaces. You are looking for an identifer like eth0, wlan0, enp3s0, wlp4s0 or tap1. For this example we’re using eth0.
Now you can connect to the IPv6 using:
ssh <username>@<ipv6 address>%<interface>
for example
ssh user@fe80::21b:21ff:fe22:e865%eth0
Replace <interface> by the correct interface (if you don’t know, try out every interface), replace <ipv6 address> by the correct IP address and replace <user> by the correct username.
If your IPv6 address does NOT begin with fe80::
You can just use
ssh <username>@<ipv6 address>
for example
ssh uli@2a01:4f9:c010:278::1
Replace <ipv6 address> by the correct IP address and replace <user> by the correct username.