Zum Inhalt


OpenWrt Upgrade auf 23.05.0 einer FRITZ!Box 4040 - Pain in the Ass!

Image by PDPics from Pixabay

Das Update meiner FRITZ!Box 4040 auf die aktuellste Version von OpenWrt 23.05.0 war diesmal ein absolutes Disaster. Update war erfolgreich, das Einspielen des Backups ein absolutes Ärgernis❗️Die Box war danach nicht mehr erreichbar, keine LED hat irgendetwas angezeigt, alles war schwarz.

Wer mit OpenWrt zu tun hat, dem ist durchaus bekannt, Upgrades auf neuere Versionen können ihre Tücken haben.

Nach Jahren der unkomplizierten Nutzung und auch Aktualisierung hat es nun auch mal mich erwischt 🤦‍♂️

Aber es gibt durchaus auch Möglichkeiten die FRITZ!Box 4040 wieder mit der Version 23.05.0 zum Laufen zu bekommen.

OpenWRT - Verschlüsselte Zeitsynchronisation mit chrony

chrony is an implementation of the NTP (Network Time Protocol). It has some advantages against the standard ntpd (= Network Time Protocol daemon).

  1. chrony can synchronize to the timeserver much faster than NTP. This is good for laptops or desktops that don't run constantly.
  2. It can compensate for fluctuating clock frequencies, such as when a host hibernates or enters sleep mode, or when the clock speed varies due to frequency stepping that slows clock speeds when loads are low.
  3. It handles intermittent network connections and bandwidth saturation.
  4. It adjusts for network delays and latency.
  5. After the initial time sync, chrony never steps the clock. This ensures stable and consistent time intervals for system services and applications.
  6. chrony can work even without a network connection. In this case, the local host or server can be updated manually.

OpenWrt - Adblock

OpenWrt offers an adblock tool and extensive block lists. It blocks adds on DNS basis like a Pi-hole. The service easy to install and to configure.

AMV Router Configuration

Configuration on an AVM router to reach a downstream OpenWrt device from your network:

  • DynDNS
  • Port Forwarding
  • IPv4 settings
  • IPv4 Routes


chrony is an implementation of the NTP (Network Time Protocol). It has some advantages against the standard ntpd (= Network Time Protocol daemon).

OpenWrt – DDNS

OpenWrt can use more than one DDNS service compared to a standard router. The setup is really easy.

Let's Encrypt

Let's Encrypt needs normally access via port 80 and 442 to the device that requests a certificate.

This article describes how to configure the necessary firewall rules.

OpenWrt - Network Configuration

Firewall, port forwarding, etc.? What and how should this get configured to make our services available?

This article describes exemplary how to make the necessary adjustments to the firewall

OpenWrt – Overview

This blog series describes the configuration of an OpenWrt device and its services to increase the functionality of an AVM FRITZ!Box 4040 home router.


OpenWrt can be configured to support encrypted DNS requests. The relevant software packages stubby and dnsmasq can be installed from the repositories.