@Thank you very much for your great help. I tried out your new node_helper.js file. Unfortunately, it still didn’t work.
I continued working with your changes and discovered the issue: I am running the very latest version of Node.js (v24). However, the node-fritzbox-callmonitor module is ancient. In the background, it utilizes a network interface that—in modern Node versions—sometimes listens to thin air if the IP family (IPv4 vs. IPv6) is not explicitly specified. It ends up silently connecting to the Fritz!Box’s IPv6 address while the incoming signal arrives via IPv4—meaning it completely misses the call notification.
Additionally, I changed the IP address in the configuration file from 192.168.1.1 to fritz.box. It seems to be working now; my blocked number is no longer being displayed. I will continue to monitor the situation and provide feedback if anything changes. Thank you very much for your work.

@Thank you very much for your great help. I tried out your new node_helper.js file. Unfortunately, it still didn’t work.
I continued working with your changes and discovered the issue: I am running the very latest version of Node.js (v24). However, the node-fritzbox-callmonitor module is ancient. In the background, it utilizes a network interface that—in modern Node versions—sometimes listens to thin air if the IP family (IPv4 vs. IPv6) is not explicitly specified. It ends up silently connecting to the Fritz!Box’s IPv6 address while the incoming signal arrives via IPv4—meaning it completely misses the call notification.
Additionally, I changed the IP address in the configuration file from 192.168.1.1 to fritz.box. It seems to be working now; my blocked number is no longer being displayed. I will continue to monitor the situation and provide feedback if anything changes. Thank you very much for your work.

Hello,
I am now certain that this issue is related to blocked phone numbers. I am using the following version:
https://github.com/xIExodusIx/MMM-FRITZ-Box-Callmonitor-py3

I attempted to modify node_helper.js to prevent these calls from being processed at all, but unfortunately, without success.

Since the FRITZ!Box sends the RING and DISCONNECT signals almost simultaneously for blocked numbers, the module triggers two notifications to the screen. The browser attempts to render two pop-ups at the same time and subsequently crashes.

Does anyone have an idea how to solve this problem?
I would greatly appreciate any input or suggestions.

The error is still there.
I think the error always occurs with spam calls. Is there a way to hide a specific phonebook?

I’ve just reinstalled the new version of drtorchwood. Let’s see if the error occurs again.

Hello
I’m running the modules MMM-FRITZ-Box-Callmonitor-py3 and MMM-Callmonitor-Current-Call. They work well. Unfortunately, there’s an occasional error.
The caller’s window gets stuck and the background remains grayed out. Can anyone help me?

Finally! After restarting it works.

New attempt: I did not install fritzconnection via pipx, but with pip. I had to turn off the “externally managed” message beforehand.
The phone book is now being read.
The call is not yet displayed. The list is only displayed after a restart.

When I try to reinstall fritzconnection I get the following message:

'fritzconnection' already seems to be installed. Not modifying existing
installation in '/root/.local/pipx/venvs/fritzconnection'. Pass '--force' to
force installation.

I installed pipx before and then “sudo pipx install fritzconnection” so I don’t need a virtual environment

I reinstalled Fritzcallmonitor. The error still exists.
During installation there were changes compared to the template:

python-dev = Doch die folgenden Pakete ersetzen es: python-dev-is-python3

sudo pip install fritzconnection  error: externally-managed-environment   sudo pipx install fritzconnection

Does anyone have any idea what I’m doing wrong?