Fritz!Box 6591 Cable, IPv6 is cut off


every time my IP is renewed, I can no longer access the server, and I finally know why.

We replaced the Fritz! Box (from DSL to cable) and since then the IPv6 has always been cut off. Half of it is simply missing.

If I log into dynv6 and click “set current address” for IPv6, it works. Before click on the button, the incomplete IPv6 was displayed, after the correct one. Then everything went well again.

My update-URL:<domain>&token=<username>&ipv4=<ipaddr><domain>&token=<username>&ipv6=<ip6addr>&ipv6prefix=<ip6lanprefix>

Thank you for help!

Unfortunately, too little information, so I have to guess.
Actually everything should work if it worked with the old Fritzbox.

If you are on the “Current status” page, which brings you to the “Edit” page, where you can click on “Set current address”, you can see that both pages say “IPv6 prefix”. So it is normal that there is only “the first half” of the IPv6 address, namely the prefix. If you click on “Set current address” on the “Edit” page, the entire current IPv6 address is displayed there (prefix + host part), but the one from the computer from which you are calling the website, not from your server or your Fitzbox. However, only the prefix is ​​used.

The IPv6 address is set on the “Resource Records” page. There should be an AAAA entry named “”. If you click on “Edit”, the name should be empty and the complete IPv6 address of your Fritzbox should be in Data.

Your server should have an AAAA entry called “”. If you click on “Edit”, the name should contain “yourserver” and the data should contain the host part of your server ("::xxxx:xxxx:xxxx:xxxx").

If you want your server to be reachable under “” instead of under “”, you do not have the full IPv6 address of your Fritzbox under “”, but the host part of your server ("::xxxx:xxxx:xxxx:xxxx"). Delete the AAAA entry with the name “” and delete the “&ipv6 = <ip6addr>” from the url in the Fritzbox .

1 Like


I might have a similar problem.

However, under records I only have For data it shows the IP address with which I can reach my Fritzbox web admin when I put it in manually (https://[IP in data:port]).
Also, it is returned when I ping
But when I put in it shows Host not reachable.


That is normal. I assume your Fritzbox updates the IPv6 address, using its own external address. For security reasons, the Fritzbox can only be reached under a randomly selected (and manually changeable) https port to make the search more difficult for automatic port scans. So you can reach the Fritzbox at https://[IPv6]:port, or

if you use without specifying a port, your browser uses the standard https port 443, on which the Fritzbox does not report! So everything normal. And should not be changed for security reasons!

1 Like

Thank you! I also had to allow ipv6 connections in my browser. Now works fine. Can VPN connections work too?

I do not understand the question. If you connect to the home network via VPN to access the Internet from home via the Fritzbox, the connection to “” works like any other website. But that makes little sense, because with a VPN the connection is sufficiently secure and since you are connected as if you were at home, you can also connect using the local address of the Fritzbox (e.g. ‘’ or ‘’). This will save you a (unnecessary) round trip through the internet. If that doesn’t answer your question, please ask a little more precisely.

However, a VPN connection via IPv6 is only possible with some (newer) Fritzboxes with lab versions of the latest firmware. And VPN over IPv4 might not be possible over cable thanks to DSLite.

1 Like

Sorry for misunderstanding! This is correct. I want to connect via VPN to remote Fritzbox which is connected with IPv6 only (DSLite-Tunnel).

Maybe it is too old (Fritzbox 6490). I will try with PiVPN. They say connection is possible.

AVM is quite good in terms of support. The chances are not that bad (the current firmware 7.29 for the 6490 is from November 9th, 2021), but it will take a while. Until then, WireGuard on a computer/Raspi in the private network is a good solution. I think WireGuard will become the standard in VPN (fast and reliable). AVM also offers Wireguard in its new firmwares.