I found an old thread from a year ago where I got it working on a Synology router. It doesn't work now. 

Waiting for their support to come back.

Ok, Synology support have changed something on my RT2600ac and now I have IPv6 native (not a tunnel, not 6to4, not 6in4). I am waiting to find out what they have changed, if this will be applied as a fix in the future, and why the IPv6 status is still showing as "Not connected" in the SRM status despite clearly having IPv6 working now.

IPv6 native (DHCPv6-PD) has been working fine for the last few days. One thing I've noticed is that if I set the LAN DHCP IPv6 as "Stateful" then Android devices won't get IPv6 addresses. If I set to "Stateless DHCPv6 mode" then they get addresses. In any case Windows devices get addresses correctly.

Also the router will show IPv4 address in the connected devices list but no IPv6 address.

The router itself will show "Disconnected" in the IPv6 status. I am told this is because "[the] router cannot get the legal prefix from the device which is in front of the RT2600ac so that the UI will show fe80 link-local connection." (as per their technical support). This to me is a bug - I don't think they understand the ONT vs modem here.

In any case I am also told a fix should be available with SRM 1.2 but no expected date for release.

I had not seen this problem with the Fritz!box 7490 or the D-Link COVR devices I have here.

Tested with both 1492 and 1508 both worked.

I didn't set any DNS, all automatic via DHCPv6-PD.

Mind you Synology did put changes into my router to test and find the problem. It seems they found it (except UI bug which is not showing the router's IP address or connection state). This means you can try but probably won't work until a later SRM is released with these changes.

freitasm:

 

IPv6 native (DHCPv6-PD) has been working fine for the last few days. One thing I've noticed is that if I set the LAN DHCP IPv6 as "Stateful" then Android devices won't get IPv6 addresses. If I set to "Stateless DHCPv6 mode" then they get addresses. In any case Windows devices get addresses correctly.

 

This is an Android problem - Google, for some strange reason, thinks that they should not properly implement IPv6 in Android, but just do the bits they think are right.  So they refuse to implement a DHCPv6 client for Android, and when challenged about it give what I consider to be rather spurious reasons.  If your Android devices are rooted, then you can install a DHCPv6 client app that fixes this.  Otherwise, you have to use SLAAC (stateless) IPv6 addressing.  Some people create a separate WiFi SSID to run Android devices on where SLAAC addressing is used, and run all other WiFi clients on an SSID where DHCPv6 is used.

IPv6 stopped working on my Synology for a few days then it suddenly came back. It appears something changed on 2degrees? HAve you changed your router setup to see if it works now?

Synology has released (and pulled) an update - apparently a new version will be coming soon.

This update seems to fix a lot of the IPv6 stuff - I'd like to believe it was my case that gave them information to get this worked on. Waiting for the update...

Ok, 1.1.7-6941-3 is released now. Installing and will check if IPv6 still working after. You should install it and try IPv6 - remember it's DHCP-PD.

freitasm:

 

Ok, 1.1.7-6941-3 is released now. Installing and will check if IPv6 still working after. You should install it and try IPv6 - remember it's DHCP-PD.

 

No joy from me sadly. DHCP-PD still shows IPV6 as disconnected.