Fritz!Box 4040 experiences

2x2 802.11ac/ wave2 results in a gross link rate of 866 MBit/s, the usable net rate of that will be around half of that at most. 300-350 MBit/s in practice is about the most you can expect from hardware like this (the interrupt handling alone will keep the CPU pretty busy; actually your wired speedtest results are already beyond my experiences with this hardware) - for (considerably) more you'd need 802.11ax/ wifi6 hardware (and/ or at least 3x3 or 4x4 clients (and APs)).

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Hello, I am trying to upgrade the firmware in my router from 22.03 to 23.05
Attended sysupgrade does not work for this major upgrade, so I downloaded the firmware from the device page (compatible with sysupgrade).

But when I attempt to flash the image (from the attended sysupgrade page) I receive this error:

Image check failed:

Thu Jan 4 20:48:17 CET 2024 upgrade: The device is supported, but the config is incompatible to the new image (1.0->1.1). Please upgrade without keeping config (sysupgrade -n). Thu Jan 4 20:48:17 CET 2024 upgrade: Config cannot be migrated from swconfig to DSA Image check failed.

It seem that I cannot keep the configuration settings due to some kind of change.

How should I deal with this in order to get the device working with the same settings?

Which are the changes that the message refers that make the config file incompatible?

I have made a backup of all the mtd blocks (16) and the configuration file, just in case.

The FB4040 has switched from swconfig (22.03) to DSA (23.05).
Backup your 22.03-settings (for reference only), sysupgrade without keeping settings and reconfigure from scratch.

Ufff, OK, thank you a lot for your answer.

I will have to take it easy, as there is time since I configured it and there are many changes to standard install (VLANS and other things).

Is there a way to have a list of installed apps that later you can send to the luci software install interface in order to reinstall them?

I have read there is te option to rename the etc/config/system and etc/config/network files and force the upgrade.
It seems that the standard files are created during boot and so you can have it running earlier, one you configured your interfaces and system options...

May be it worths try if the system does not brick.

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luci-app-attendedsysupgrade in advanced mode should offer you the choice of downloading the sysupgrade image with all the currently installed packages. Then sysupgrade w/o keeping settings.

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Thanks a lot, will try

I have tried, but I have a problem:
when I tried to build the firmware for the packages I have installed in the system I receive an error:

Server response: Error: Impossible package selection

I suspect it is due to swconfig being incompatible with 23.05 firmware version.

So I should delete swconfig from the list of packages to build, but, which packages should I add instead?

Which is the dsa switch package ? Is that the only change I whould do?

Thank you

you can try the following command to find installed packages:

ps: I advise you to proceed with installing the packages that you think are necessary for the router and not all those that it might give you


FLASH_TIME=$(opkg info busybox | grep '^Installed-Time: ')

for i in $(opkg list-installed | cut -d' ' -f1)
    if [ "$(opkg info $i | grep '^Installed-Time: ')" != "$FLASH_TIME" ]
        echo $i