The latest lab file on our download server, "fritzbox-7520_B-labor-xxxxx.zip", contains
- the lab version for FRITZ!Box
- this "infolab.txt" file with important information on this lab version
- Information, feedback options and the file at en.avm.de/fritz-lab


Neue Features: 
- New Online Monitor with expanded functions
- Optimized parental controls
- New upload sharing - Sharing files easier than ever
- More possibilities in the smart home
- Supplementary services for the SIM card's mobile number
- Text-based caller greetings (text-to-speech)


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I. New Features, Improvements and Updates in this Lab
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# New Features and Improvements in FRITZ!OS 8.21
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This FRITZ! Lab contains new functions fresh from the FRITZ! development team and gives a preview of upcoming FRITZ!OS features in the next major update. It also contains the latest developments in the areas of security and energy efficiency.

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# New Features in FRITZ!OS 8.21

## Internet:
- **NEW** Simplified user guidance on the "Filter" pages (parental controls) (more [1])
- **NEW** Online Monitor shows the network devices with the highest use of the internet connection (top consumers) (more [4])
- **NEW** Additional display option in the Online Monitor of individual devices shows usage by not explicitly selected devices with and without data recording (more [4])
- **NEW** In the Online Monitor the display of the load on the internet connection allows selection of not only one day or two months but also an interval of 2 weeks (more [4])
- **Improvement** Automatic adoption of the MTU size from the mobile network for IPv4 and IPv6
- **Improved** Device selection for display and data recording simplified in the Online Monitor
- **Improved** Reworked diagrams and colors in the Online Monitors
- **Improved** Completely reworked network settings
- **Improved** In the settings for parental controls can now be specified whether network applications are blocked or allowed
- **Improved** Online time for a network device with restricted online time now can also be extended for 45 minutes directly in the parental controls
- **Improved** If the configured time server could not determine the system time, the system time is obtained from a public time server
- **Improved** Number of tickets to extend online time for devices blocked by parental controls was increased from 10 to 12
- **Improved** Online Monitor: Reworked display in the diagrams for the load on the internet connection
- **Improved** Performance improvement during many parallel DNS queries
- **Changed** When VPN connections are active for which all network traffic is routed via the VPN connection ("full tunnel"), the guest network is excluded from this and routed over the normal internet connection
- **Changed** FRITZ! devices in the home network, e.g. FRITZ!Repeaters, are no longer offered in parental controls and prioritization; they always have unrestricted internet access with normal priority
- **Changed** Private IPv4 addresses (RFC 1918) are no longer posted via MyFRITZ!Net (DNS) if a publicly accessibly IPv6 address is available

## Wi-Fi:
- **Improved** Increased stability in Mesh Repeater mode
- **Improved** Better stability
- **Changed** Incongruous information text for configuration of the Wi-Fi guest access on the Mesh Repeater removed

## Mesh:
- **NEW** Automatic detection of device type (e.g. smartphone, computer, or printer) for devices displayed in the Mesh Overview

## Telephony:
- **Improvement** Support for hold, query call, and call brokering when using the SIM card's mobile number (VoLTE)
- **Improvement** Telephone connections via the SIM card's mobile number are displayed in the VoIP quality display
- **Improved** Support for text-based caller greetings (text-to-speech) for the integrated answering machine
- **Improved** Support for the Vodafone IP Anlagen Anschluss
- **Improved** Increased stability of telephone calls

## DECT/FRITZ!Fon:
- **Improved** Podcasts can now be continued after interruption

## Home Network:
- **NEW** EEE (Energy Efficient Ethernet) can now be set separately for each WAN/LAN port

## Smart Home:
- **NEW** Routines can also be triggered by a phone call, by reaching a target temperature, or by activating boost or antifreeze functions, as well as by important events on the FRITZ!Box (more [3])
- **NEW** With FRITZ!Smart Control 440, the following functions can be controlled: the boost and frost protection functions for radiator controllers, the color and color temperature for lamps, the activation and deactivation of routines, and the display of the QR code for Wi-Fi
- **NEW** Templates and routines can be triggered with delay 
- **NEW** Data read by the FRITZ!Smart Energy 250 from the export meter is shown in the menu under "Smart Home > Devices and Groups"
- **NEW** In the FRITZ!Box user interface of the Mesh Master, the registration of smart home devices with another FRITZ!Box or a FRITZ!Smart Gateway can be started

## Storage (NAS):
- **New** Upload sharing: Via fritz.nas a folder can be shared for users with a sharing link to upload and download contents, e.g. to collect photos after a family celebration (more [2])
- **Improved** Better interoperability with FTP applications (e.g. Filezilla) through support for MFMT command
- **Improved** Simplified generation of sharing links

## System:
- **NEW** Push service mails for logins by apps to the FRITZ!Box
- **Improved** "Forgot Password" function of the push service can now be configured with a freely chosen recipient
- **Improved** File name for saved settings now includes name of individual FRITZ!Box
- **Improved** Reworked pages of the update functions under "System > Update"
- **Improved** With "Diagnostics > Function" the services for the Network Time Protocol are checked and relevant information displayed about any errors found
- **Improved** Functional diagnostics now indicates when access for apps is disabled in the home network sharing settings
- **Improved** The "Diagnostics > Function" page now displays information on problems with time synchronization via NTP
- **Improved** Indication of disabled TR-064 added to the Function diagnostics
- **Improved** The probability of being logged out prematurely from certain pages of the user interface was reduced
- **Improved** Push service emails now clearly differentiate between function and security diagnostics through specific subject lines, adapted email texts, and file names
- **Improved** Changes to LED brightness are much more visible

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[1] Optimized parental controls

A number of practical optimizations have been included in the first version of FRITZ! Lab. The parental controls now clearly display access profiles and the corresponding devices on one page. Tickets for online time are easier to find on a separate tab and the number of tickets was increased from 10 to 12. This makes managing family internet usage even simpler and more intuitive. Detail improvements were also made to the Online Monitor area. The line graphs have been color-optimized for an even clearer display, and the tooltip that is now is easier to read provides users with more information about the Online Meter.

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[2] New upload sharing  - Sharing files easier than ever

With the new upload sharing via FRITZ!NAS, sharing files has never been easier: Users can make a folder available via sharing link, allowing others to directly upload and download content   perfect for collecting shared photos or documents. Thanks to the new function, it is no longer necessary to create a FRITZ!Box user with special write permission   instead, all that is needed to allow friends and family to securely upload files is a single link.

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[3] More possibilities in the smart home

The update also brings additional control functions for the FRITZ!DECT 440 smart switch. Now all the functions that could be configured directly on the radiator control FRITZ!Smart Thermo 302 can also be controlled with the smart switch. In addition, it now offers more comprehensive options for lighting control. Besides switching on and off and dimming, it can now be used to change the color and color temperature. In addition, routines can now be activated and deactivated directly using the FRITZ!Smart Control 440. Routines can also be triggered by a call, reaching a target temperature, activating the boost or antifreeze function, as well as by important events on the FRITZ!Box. To make managing Wi-Fi even simpler, the FRITZ!Smart Control 440 can be used to switch off the main Wi-Fi network in addition to guest Wi-Fi.

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[4] New Online Monitor with expanded functions

The new Online Monitor shows which network devices are using the internet most intensively.
The views for the 'Total' utilization, the 'Top Consumers' and the individual devices allow the display to be restricted to certain time periods. The display periods that can be selected are 10 minutes, one hour, one day, and two months, and now also the past two weeks.
The selection of network devices for which the utilization data are to be recorded and displayed has been simplified considerably in the new version, and is now performed completely in the Online Monitor.

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History of New Functions and Improvements in FRITZ!OS 8.24
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# Further Improvements of FRITZ!OS 8.24-130235
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## Internet:
- **Changed** Root certificate added for DNS over TLS with SSL.com
- **Improved** Better interoperability with newer browser versions
- **Improved** Detailed rendering of fallback protection in Online Monitor
- **Improved** Operation of schedules in the parental controls reworked for small displays (smartphones, tablets)
- **Improved** Support for fallback protection also for primary internet connections with a fixed IP configuration
- **Improved** Support of IPv6 configuration for fallback protection
- **Fixed** The "Fixed bandwidth reservation for the home network" option did not always work
- **Fixed** Internet access (remote access) to the FRITZ!Box could be configured only while the FRITZ!Box was connected to the internet
- **Fixed** The summary of individual access profiles for parental controls displayed "No restriction" despite restrictive settings
- **Fixed** When the standard profile in the parental controls was blocked, sometimes authorized devices could no longer register with the Wi-Fi network
- **Fixed** In the Connection Details in the Online Monitor, the status of the WAN connection was sometimes displayed as inactive despite an active internet connection

## Telephony:
- **Changed** Root certificate added for encrypted VoIP with SSL.com

## Home Network:
- **Fixed** In special scenarios it was possible for the IP address 192.168.178.1 to be displayed for an extender in the home network instead of its own address
- **Fixed** Names of home network devices were occasionally assigned incorrectly
- **Fixed** Under some circumstances active devices with static IP addresses were displayed as inactive and vice versa
- **Fixed** In certain scenarios, unnecessary entries for switches (FA:CE:...) were displayed in the idle connections section

## System:
- **Improved** More robust error handling during the update search
- **Improved** Stability
- **Fixed** With very slow internet connections, a FRITZ!OS update could sometimes be prematurely aborted via the user interface

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Further Improvements of FRITZ!OS 08.24-130235
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initial lab version


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III. Additional Feedback on FRITZ!OS
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In addition to direct feedback in our lab area en.avm.de/fritz-lab, there are three additional feedback functions in the user interface which provide information. We have automated the processing of feedback supplied by these functions.

1) DSL feedback via "Internet / DSL Information / Feedback"
2) Wi-Fi feedback via "Wi-Fi / Wi-Fi Network": Feedback icon after the clients
3) VoIP feedback via "Telephony / Telephone Numbers / Voice Transmission", "Other" column: Feedback icon after each call


IV. Information on the Lab Update
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This FRITZ! Lab firmware is a beta version. AVM tested the software in standard environments before making it available to the public, but it may still result in malfunctions. AVM will not be liable for any damages that arise from the use of the lab version.

Information on Working with Lab Versions

We appreciate any feedback from our users, which can be submitted on the page en.avm.de/fritz-lab.
This page also presents all of the current FRITZ! Lab versions with corresponding feedback areas.

Before You Start Testing the Lab Version

1) You have not installed the latest firmware for your FRITZ!Box yet? Then you must first update the firmware to the latest release.
2) Save your current settings under "System / Backup". The saved settings will be needed if you want to switch back from the lab firmware back to the release firmware.


Testing the Lab Version

Once the latest firmware has been installed on your FRITZ!Box and you have saved your current settings, you can begin testing.

1) Unzip the "fritzbox-7520_B-labor-xxxxx.zip file".
2) Use the FRITZ!Box user interface to install the update:
- Select "View: Advanced" in the footer.
- Navigate left in the menu to "System / Update".
- Switch to the "FRITZ!OS File" tab.
- Follow the instructions displayed on the screen.
Enter in the input field the path to the lab firmware and the name of the firmware itself (FRITZ.Box_7520_B-08.24-xxxxx-LabBETA.image).
3) The firmware is transferred to the FRITZ!Box. Then the FRITZ!Box will restart.


Restoring Your Device to the Condition It Was in Before Testing

You can restore the official FRITZ!OS to your FRITZ!Box at any time under "System / Update / FRITZ!OS Version", or reset the FRITZ!Box using the included Windows program "FRITZ.Box_7520_B-08.21-recover" (included in the lab package).

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© FRITZ! GmbH 2004 - 2026. All rights reserved.

This FRITZ! firmware package contains files that are propagated under different licenses, in particular under a license held by FRITZ! or under an open-source license (the GNU General Public License, GNU Lesser General Public License or FreeBSD License). For details on the various licenses, see the "license.txt" file (https://download.avm.de/fritzbox/license.txt).
The source code of the files propagated as open source files can be obtained upon a written request to fritzbox_info@avm.de.

FRITZ! grants the non-exclusive right to use this FRITZ! firmware package, which is supplied exclusively in object code format. The licensee may create only one copy of the software, which may be used exclusively for backup use.
FRITZ! reserves all intellectual property rights except as expressly granted herein. Without previous approval in writing, and except for in cases permitted by law, it is particularly forbidden for this FRITZ! firmware packet to be
- copied, propagated, or in any other manner made publicly accessible, or
- processed, disassembled, reverse engineered, translated, decompiled or in any other manner "opened" and subsequently copied, propagated or made publicly accessible in any other manner.
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TVI 2026-03-13