DynDNS Update Fails with rcode=NOTIMP on YunoHost 12.1.6.1

Support
,
1

What type of hardware are you using: Old laptop or computer
What YunoHost version are you running: 12.1.6.1
How are you able to access your server: The webadmin
SSH
Direct access via physical keyboard/screen

Describe your issue

Hello YunoHost Community,

I’m encountering an issue when trying to update my DynDNS record using the CLI command:

yunohost dyndns update --force

The output is:

Info: Updated needed, going on…
Fehler: id 22483
opcode UPDATE
rcode NOTIMP
flags QR
;ZONE
;PREREQ
;UPDATE
;ADDITIONAL
Info: The operation ‘Update IP address linked to YunoHost subdomain uwu.noho.st’ could not be completed.
Please share the full operation log for help.
Fehler: Could not update the IP address for DynDNS

Context and troubleshooting so far:

This DynDNS update process was working without issues before I switched my network to use a Ubiquiti Cloud Gateway Ultra.

DNS resolution to the nameserver (ns.noho.st) works perfectly (dig @ns.noho.st uwu.noho.st A returns the correct IP).

Both TCP and UDP connections on port 53 to ns.noho.st are successful (nc tests).

Firewall and iptables on the Ubiquiti gateway do not appear to block DNS traffic on port 53.

I suspect the Ubiquiti gateway might be interfering with DNS UPDATE packets or modifying the packets, causing the rcode NOTIMP (Not Implemented) error from the nameserver.

Has anyone seen this error happen after introducing a Ubiquiti gateway? How can I confirm if the gateway is blocking or altering DNS UPDATE requests? Any advice on making DynDNS updates work again with this gateway?

Thanks in advance for your help!

Share relevant logs or error messages

https://paste.yunohost.org/raw/egozigevow

2

Hello everyone,

I wanted to share a solution to a problem I’ve been struggling with for a while, in case anyone else encounters it.

Problem Description: My Yunohost instance (version 12.1.6.1) was unable to update its DynDNS entry for *.noho.s (using noho.st as the DynDNS service). The yunohost dyndns update --force command consistently returned the following error in the logs:

Fehler: id XXXX opcode UPDATE rcode NOTIMP flags QR ;ZONE ;PREREQ ;UPDATE ;ADDITIONAL Error: Could not update the IP address for DynDNS

This issue started occurring after I replaced my router with a new Ubiquiti Cloud Gateway Ultra (UCG Ultra). My Yunohost server is connected to this gateway. The rcode NOTIMP (Not Implemented) error was particularly puzzling, as it implies the DynDNS server didn’t understand the update request, which is highly unusual for a standard service.

Troubleshooting Steps (and what did NOT work):

  1. Verified Yunohost’s external IP detection: curl https://ip.yunohost.org showed the correct public IP.
  2. Confirmed DynDNS entry needed update: dig A *.noho.st @ns.noho.st showed an old IP address.
  3. Checked network connectivity: ping ns.noho.st and nc -zv ns.noho.st 53 from the Yunohost server confirmed that the server could reach the DynDNS host on port 53 (UDP/TCP).
  4. Bypassed Gateway’s DNS Proxy: Temporarily configured Yunohost’s /etc/resolv.conf to use external DNS servers directly (9.9.9.9 and 1.1.1.1) instead of the gateway. This did not solve the problem, indicating the issue wasn’t the gateway’s DNS relay function.
  5. Disabled Ubiquiti’s “Threat Management” (IDS/IPS): In the UniFi Network Application, I navigated to Settings > Security and turned off "Intrusion protection (Intrusion Protection). This also did not solve the problem.
  6. Checked UniFi Firewall Rules: No explicit firewall rules were found that would block or modify outgoing DNS traffic.

The Solution:

After exhausting other options, the problem was finally resolved by disabling “Ad Blocking” in the Ubiquiti Cloud Gateway Ultra.

Steps to disable:

  1. Log in to your UniFi Network Application.
  2. Navigate to Settings > Security.
  3. Locate the option “Ad Blocking” and uncheck / disable it.
  4. Apply/Save the changes.

Immediately after disabling Ad Blocking, running yunohost dyndns update --force was successful!

Why this happened: It appears that Ubiquiti’s “Ad Blocking” feature, contrary to a simple DNS filter, somehow interferes with or modifies the specific DNS UPDATE packets used for DynDNS, causing the remote DynDNS server to respond with rcode NOTIMP.

Conclusion: If you’re using a Ubiquiti Cloud Gateway (or similar UniFi OS devices) and experience rcode NOTIMP errors with DynDNS updates from your Yunohost, check your gateway’s “Ad Blocking” setting.

Hope this helps someone else!

Best regards,