I'm trying to set up three cloud routers inside Vultr.

They only use ND advertisements for IPv6 and will not provide next hop information - so I am at their mercy.

The configuration below worked for a few hours on one server, but after a reboot stopped. All three routers are identical (bar IPv6 address)

# nov/07/2016 21:15:01 by RouterOS 6.38rc25
# software id =
#
/ipv6 address
add address=2001:19f0:5801:233:5400:ff:fe3f:e044 interface=ether1
/ipv6 nd
set [ find default=yes ] disabled=yes managed-address-configuration=yes other-configuration=yes
add hop-limit=64 interface=ether1
/ipv6 settings
set accept-router-advertisements=yes max-neighbor-entries=1024

If you end up here trying to get IPv6 working at Vultr - from a clean build - the commands below work.
The order they are issued appears to be exceptionally important.

/ipv6 address
add address=[[YOUR IPv6 ADDRESS] interface=ether1
/ipv6 nd
set [ find default=yes ] disabled=yes
add interface=ether1
/ipv6 settings
set accept-router-advertisements=yes forward=no

Why do you need IPv6 if you disable its forwarding?

By chance is this still working? I cant seem to get this solution working with vultr..

My latest attempt at a working config includes this:

/ipv6 address
add address=2001:19f0:8001:10:5400:00ff:fe71:a757/64 advertise=yes disabled=no eui-64=no from-pool="" interface=ether1

/ipv6 nd
set [ find default=yes ] advertise-dns=no advertise-mac-address=yes disabled=yes hop-limit=unspecified interface=all \
managed-address-configuration=no mtu=unspecified other-configuration=no ra-delay=3s ra-interval=3m20s-10m ra-lifetime=30m \
reachable-time=unspecified retransmit-interval=unspecified
add advertise-dns=no advertise-mac-address=yes disabled=no hop-limit=unspecified interface=ether1 managed-address-configuration=no mtu=\
unspecified other-configuration=no ra-delay=3s ra-interval=3m20s-10m ra-lifetime=30m reachable-time=unspecified \
retransmit-interval=unspecified

/ipv6 nd prefix default
set autonomous=yes preferred-lifetime=1w valid-lifetime=4w2d
/ipv6 settings
set accept-redirects=no accept-router-advertisements=yes forward=no max-neighbor-entries=8192

But still no luck... :/