DynDNS with IPv6 on EX3600-T0


I have a DynDNS provider (inwx.com) that is not listed in my EX3600-T0, which is why I created a user defined DynDNS entry with the following settings.

Service Provider: DNS user defined
Connection Type: HTTPS
URL Update: dyndns.inwx.com/nic/update?myip=<ipaddr>&myipv6=<ip6addr>
Username: <USERNAME>
Password: <PASSWORD>

The IPv4 address gets set as expected, but the IPv6 doesn't.
(The IPv6 address/prefix is provided by my provider via DHCPv6)

My questions regarding this are:
- Are there any known issues on this topic?
- Is there any way to get more detailed information about what's happening? Even with log settings turned to 11, I can't see any DynDNS-related entries.

All Replies

  • tonygibbs16
    tonygibbs16 Posts: 836  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    edited February 28

    Hello @Falko

    Welcome to the forum.

    Are you able to say what firmware version is running in your EX3600-T0 please?

    Are you also able to say what the status part of the DynDNS page says, about user authentication status, last updated date, and current dynamic IP is?

    Looking at the INWX knowledge base for DynDNS, it seems that the setup example for a Fritzbox has the &myipv6= but that the setup example for TPLink does not.

    - see https://kb.inwx.com/en-us/8-dyndns

    Some one else was trying to setup DynDNS with a Zyxel VMG3925 at https://superuser.com/questions/1538229/how-can-i-set-up-custom-dynamic-dns-on-a-zyxel-vmg3925

    Kind regards Tony

  • Falko
    Falko Posts: 3
    Friend Collector First Comment

    Hej @tonygibbs16 , @BookerE1 ,

    thank you for all your answers. The answers to your questions are further down. I was able to (probably) find the problem:

    I changed to server to a machine in the network and traced the http request there. It looks like this:

    falko@raspi:~ $ sudo nc -l 80
    GET /nic/update?&myip=<ipaddr>&myipv6=<ip6addr>&hostname=star-fleet.space& HTTP/1.1
    Authorization: Basic [REMOVED]
    User-Agent: ez-update-3.0.11b8 aarch64-openwrt-linux-gnu [] (by Angus Mackay)

    As you can see, the fields <ipaddr> and <ip6addr> were both not substituted with the respective addresses. Updating the IPv4 address must therefor be done through the source IP address. In the "superuser" link provided by @tonygibbs16 is a link to a ZyXEL 5501 documentation in which at least the "ipaddr" filed is mentioned. It seems this feature is not present any longer.

    If anyone responsible from Zyxel is reading here, it would be a delight if you could implement the substitution or document if I used the wrong field names.

    However, left without hope to find a quick solution, I'll implement an updater myself in the following days/weeks. Will post it here as soon as it is done.

    Kind regards,


    Answers to your questions :

    • Firmware Version is V5.70(ACIF.0.1)D0
    • "User Authentication Result" is "Accepted", "Last Updated Time" is "Feb 28 21:28:08", and "Current Dynamic IP" is the expected ip

  • While you or penalty shooters 2 mentioned that the logs don't show DynDNS-related entries, make sure you are looking in the right place. Some routers have separate sections for dynamic DNS logs or may categorize them under a broader term like "WAN" or "Internet" logs.

  • tonygibbs16
    tonygibbs16 Posts: 836  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer

    You're welcome @Falko

    If you are looking to use an updater on a separate Linux server, then maybe inadyn would be helpful to you, see https://manpages.ubuntu.com/manpages/focal/en/man8/inadyn.8.html#:~:text=inadyn%20is%20a%20client%20for,more%20domains%20to%20choose%20from.

    Otherwise Zyxel need to say what tags to use in the EX3600-T0 and if it works for IPv6.

    Kind regards,


  • Falko
    Falko Posts: 3
    Friend Collector First Comment

    Just a quick follow up on how the situation developed. tl;dr: I stopped trying to find a solution and am deeply disappointed.

    The solution mentioned here won't fix my problem, since I want to set the DynDNS entry to my routers IPv6 address, not to an address from the prefix that is assigned to me. So, using an updater that relies on the clients v6 address won't work.

    I wanted to write a program that logs in onto the router, reads out the addresses and update the DynDNS entry. The problem with this approach are:

    - The SSH implementation on the server does not allow for simple commands to be given to the connection, one has to always implement a pseudo terminal and parse the output from there. That not an effort I am willing to spend on this problem. This was the problem that made me stop working on the whole issue.
    - SSH does not support public key authentication. No dealbreaker, but also not nice.
    - The user management does not support non-administrative users to log in via SSH. This would have been a real security problem that would have required a lot of caution.

    Furthermore, as it can be seen in my post from 2024-02-28, the router internally uses the OpenWRT Linux distribution and the "EZ-Update" or "Ez IP update" from Angus Mackay. This program seems to be abandoned, and we cannot expect security updates to be delivered any longer. (Please correct me if I just didn't find the right spot).

    And lastly, since it uses with Linux and EZ-Update at least two programs under the GPL, I would expect some license information on these programs. I never found these anywhere, so one has to assume that Zyxel violates the GPL here. Once again: Please correct me if I just had no luck finding the informaiton.

    After all, this was just too much to continue implementing a solution.

    The money spend on my EX3600-T0 was completely wasted.

    This machine is barely usable for consuming FaceTube. If you want something usable, buy a router that can be used with OpenWRT that you can install yourself.

    So long,


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