Hello, gurus of ROS,

I have Mikrotik RB3011UiAS-RM and Mikrotik Hap ac routers.
I got /56 prefix from ISP and all clients, connected to RB3011UiAS-RM works with IPv6 very well, except Hap ac Hap ac even not to accept RA, and no global adresses assigned.
What is traditional routing schema to propagate IPv6 to the second router?

P.S. prefix and addresses is dynamic...

DHCPv6 PD

Just take the address manually on hap ac.

If you also need a prefix - run dhcpv6 on 3011.
But only prefix delegation (or info) is working for now, not handing addresses.

P.S. prefix and addresses is dynamic...

Get the prefix on hap ac from 3011 then, and let it chose address from the pool.

Hap ac even not to accept RA

Routers are not supposed to get addresses from RA. It's possible to override it (see accept-router-advertisements in /ipv6 settings), but it probably only makes sense when the second router would be just AP and not routing, i.e. for management purposes. If you need another IPv6 subnet behind the router, then it's either DHCPv6 PD or static config.

Thank you very much. I reconfigure to use DHCPv6 server (only prefix) from Hap ac, and it's working well.

In IPv6 you think in prefixes which are basically networks that are divided into smaller subprefixes: first 64 bits are prefix, second 64 bits are client.

Usually prefixes are shared and divided using Prefix Delegation. Process goes like this: you ask prefix from ISP using DHCPv6 Client and in this first step you do lots of substeps 1) you get prefix 2) you create address pool of it and 3) you set the size of subprefixes (Pool Prefix Length) you will share further. If you don't set the pool prefix length then smallest aka /64 prefixes are shared. In your example you get /56 which means you can share/divide it into 64-56=8 -> 256 subprefixes. To share subprefixes further you must start DHCPv6 server in the first router. To set IPv6 number for the router's interface you just add IPv6 address from created pool.

When the second routers wants to share IPv6 numbers it does the same as the first one: it asks for IPv6 prefix from the first router using DHCPv6 Client and gets subprefix the length you set in first router's DHCPv6 Client.