IPv6 with Vodafone Station (Czechia) borked

RouterOS Beginner Basics
1

Is it possible to get IPv6 working when using Vodafone Station in Czechia? If I connect my Linux PC directly to the Vodafone Station modem/router, my IPv6 works fine. But if I connect my PC to Mikrotik CRS112-8P-4S, 7.11.2 software, no matter the settings I change on the Mikrotik, I can’t get IPv6 working on the PC.

If I try to use Automatic configuration of IPv6 on Linux, which I assume is SLAAC, I get following issue with increasing timeout in my logs, and eventually, the system resets the connection and tries again.

NetworkManager[2140]: <debug> [1696780615.7744] ndisc[0x556213091af0,"enp6s0"]: solicit: schedule sending next solicitation in 237.052 
seconds

I also tried DHCPv6, and I do get an address from the Vodafone Station. But then I do not get any routing or forwarding from the Mikrotik for the IPv6.

I fiddled with the Mikrotik IPv6 settings and I tried pretty much all combinations of the options in the IPv6 Settings dialogue in WinBox.

I also tried to turn on/off Neighbor Discovery and I fiddled with its settings, no dice.

What gives? What is the secret sauce to get IPv6 working in my situation? Has anyone tried with Vodafone Station in Czechia?

2

Are you using the CRS as a bridge or a router? AFAIK mobile operators only provide a single /64 and no prefix delegation. As you need one /64 per network using the CRS as a router will not work unless you resort to NAT (which IPv6 was supposed to do away with).

3

I am using it as a bridge.

4

It should pass IPv6 OK - however if you have DHCP or IGMP snooping enabled it may break IPv6 multicast, IIRC there have been some forum posts about this.

For the CRS to obtain an IPv6 address disabling IPv6 forwarding will enable it to process RAs.