Mikrotik: how to properly setup IPV6 routing/dhcp server

I have the following configuration in my network:

ISP Router <- eth1 -> Mikrotik Router <- eth2-5 -> Internal network

My ISP router receives a /64 IPV6 block that is dynamic, changing whenever I reboot it.

The issue is that the devices in my internal network aren't receiving an IPV6 address, probably because the DHCP server in Mikrotik isn't configured correctly.

I already configured the DHCP client in Mikrotik ( IPV6 -> DHCP client ) and I can see the /64 block that was assigned by my ISP.

But I can't configure the DHCP Server. I tried to assign the pool in "IPV6 -> DHCP Server -> Add new" but my devices still doesn't receive any IPV6 addresses.

Any ideas about what is wrong? I'm using version 6.33.

Note: If i connect a device directly to my ISP router, IPV6 works correctly.

--- Edit ---

After Michael comment I was able to make some progress. I disabled the DHCP Server in Mikrotik and added a new address in "IPV6 -> Addresses" with advertise flag and using the pool that is created by the DHCP client.

All devices in my internal network are receiving IPV6 addresses and can ping each other. Unfortunately I can't ping external hosts.

In Mikrotik I can only ping external hosts only if I check the option "Request address" in /ipv6 dhcp-client. Otherwise ping doesn't work in Mikrotik.

Example: trying to ping ipv6.google.com.

/ping 2800:3f0:4001:801::200e
  SEQ HOST                                     SIZE TTL TIME  STATUS
    0 2800:3f0:4001:801::200e                                 timeout
    1 2800:3f0:4001:801::200e                                 timeout
    2 2800:3f0:4001:801::200e                                 timeout
    sent=3 received=0 packet-loss=100%

Here is how my route looks like:

/ipv6 route> print
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable
 #      DST-ADDRESS              GATEWAY                  DISTANCE
 0 ADS  ::/0                     fe80::e297:96ff:fe6a:...        1
 1 ADC  2001:1284:****:90dd::/64 ether2-master-local             0
 2  DSU 2001:1284:****:90dd::/64                                 1 

Mikrotik does prefix delegation only. Its dhcp server implementation is incomplete. I've been following the discussions on their forums. See http://forum.mikrotik.com/viewtopic.php?f=13&t=101918&p=506310&hilit=dhcpv6#p506307.