IPv6 BGP on Vultr shows this error:
```
BGP: 2001:19f0:ffff::1 [Event] Connect start to 2001:19f0:ffff::1 fd 11
BGP: 2001:19f0:ffff::1 went from Idle to Connect
BGP: 2001:19f0:ffff::1 open active, local address 2001:19f0:6c01:65c:5400:1ff:fe38:54c4
BGP: 2001:19f0:ffff::1 sending OPEN, version 4, my as 64714, holdtime 180, id 45.77.143.163
BGP: 2001:19f0:ffff::1 send message type 1, length (incl. header) 53
BGP: 2001:19f0:ffff::1 went from Connect to OpenSent
BGP: 2001:19f0:ffff::1 rcv message type 3, length (excl. header) 8
BGP: 2001:19f0:ffff::1 received NOTIFICATION 2/7 (OPEN Message Error/Unsupported Capability) 6 bytes 01 04 00 01 00 01
BGP: 2001:19f0:ffff::1 went from OpenSent to Idle
```
https://tools.ietf.org/html/rfc7911