Fritz!Box 4040 experiences

I was very thrilled when the Fritz!Box 4040 was supported by OpenWrt. The Fritz!Box Hardware has frequently been attributed as "solid" in reviews and I have always liked their relatively unobtrusive design. And the 4040 is comparatively cheap.

After having used one of these as an access point without any problems for about a year, I decided to use another one as my central router when my cable provider upgraded to 500/25. This turned out to be a bad decision.

The instability problem (which I only search for and found out about after experiencing it myself) has been described here and here

I've created this thread to add some information related to performance. Using all LAN, of course, my provider's speedtest never showed more than 300 Mbit/s. produced varying measurements but never more than 130 Mbit/s, which I attributed to a (presumably) bad connection between my provider and the servers.

Because of the instability issue, I have replaced the 4040 with a ZyXEL NBG6817. Now I get 480 Mbit/s using my provider's speedtest and 360 Mbit/s using

I don't know if this is related in any way to the instability issue. But at least with 19.07.2 and higher connection bandwidth, the Fritz!Box 4040 is cheap, but not a good bargain.

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I'm also using a FB4040, but had no issues with Youtube videos at all.
You might also have a look here:

Would be interesting to know if other ipq40xx based suffer the same issue on 19.07.x


As described at the referenced locations, I didn't have issues with YouTube videos either. The LAN interface stopped working arbitrarily, not necessarily related to heavy traffic.

Same speed problem here with the latest 19.07.3.

Good morning here from Germany!
I think I've resolved the problem. It has to do with the cpu governor scaling setting. It's set to "ondemand" which is good for high performance cpus respectively in laptops or desktops. I achieved nearly gigabit speed with the following settings:

  1. Enable "Software flow offloading" in Network -> Firewall -> Routing/NAT Offloading
  2. Add the following line to System -> Startup -> Local Startup before 'exit 0'
    echo performance > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
  3. Disable SQM QoS if you are using it!
  4. Install the irqbalance package. System -> Software -> Filter irqbalance -> Install
  5. Reboot your FritzBox.

Now test your internet speed.

Kind Regards

Update: Install irqbalance package.

I don't have the fb4040 in use any more. But when I enabled "Software flow offloading" back in May (of course I tried that), the box hung almost immediately.

No Problem here with latest 19.07.x build

No Problem here with latest 19.07.x build

Obviously :wink:. If enabling "Software flow offloading" also fixes the instability issue, then you might be lucky and this feature works around the buggy code executed otherwise.

Note that the general instability (in my case) occurred randomly. Sometimes things worked fine for several days and I couldn't reproduce it by navigating to a specific YouTube video. So keep watching. And if possible, confirm your finding here when your box has been running a month without problems.

Hello from Germany too,
I am going to try to do the same.
My first speed medicine test was better for me, I hope it is stable.
This command is well executed:

# Put your custom commands here that should be executed once
# the system init finished. By default this file does nothing.
echo performance > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
exit 0

where it is disabled:

Hello, does Fritzbox 4040 support Distributed Switch Architecture (DSA) with release 21.02 or the old swconfig? Thank you!

fritzl, old swconfig, as mpa wrote here


Hi there. I'm desperately trying to install the latest OpenWrt on my new Fritz!box 4040 but no luck so far sadly. The instructions on the device page don't need seem to work for me, neither the fritz-tools route not the manual FTP route. The fritz-tools never completes the autodiscovery phase, and via the manual FTP route I can't seem to get an FTP connection established. For the latter, I'm aware of the limited time window during boot when the connection needs to be initiated. On Ubuntu, I let a ping command run during the booting of the Fritz!box and as soon as I get a reply I run "ftp -n -v -p" in a separate terminal but unfortunately "Connection refused".

I found another thread ( Fritzbox 4040 flash: FTP connection refused ) where I think the same problem was discussed, and there it was suggested that this is due to more recent firmware requiring a special UDP packet containing the IP address from which the FTP connection will be initiated to be sent first. There is a link to a bash file which should be doing that: . I thought I would first run it just to see if it reports finding the EVA, and if that works then run it again with the HOLD parameter of the script set to 1 which apprantly keeps the EVA open after which an FTP connection can be established.

However despite a number of tries running that bash file immediately after powering on the Fritz!box it never seems to be able to find a running EVA bootloader...

Does anybody here have any suggestions what I'm doing wrong or alternative approaches?

You could try the AVM (Windows) Recovery Tool for another (wrong) Fritzbox.
I've done this successfully with the recovery tool for a Fritzbox 4020.
The tool will tell you, that it's not the correct one and finish, but now the bootloader is ready for you ftp in.
On Windows you need a ftp client that supports passive mode (the builtin doesn't)
I used this one:


Thanks Thomas! Unfortunately I don't have any Windows machines (and it's been a while since I really used one) -- would you happen to know whether that recovery tool and a subsequent FTP connection could in principle be done via Wine for instance?

As I only run Debian without desktop (openmediavault) it don't know if wine would be working.
If wine does not work, my next idea would be Virtual box and a full windows installation.


I fully agree with tomtom. Switch back to stock firmware with a full Windows installation and Fritz recovery tool and try to reflash with manual ftp method as discribed on the OpenWRT Fritzbox 4040 Mainpage. I upgraded successfully with these steps to 21.02. I opened two terminals. One with ping and another with ftp connect. No problem so far.

Thanks frtizl (:no_mouth:) -- there's in my case no switching back as it is a new device with still the vendor OS on. Interesting that the standard method works for you while I can't seem to get it to work and that's not for a lack of trying/tinkering. Anyhow, as soon as I have another moment I'll try the AVM recorvery tool for a different device method via Wine -- found an entry in WineDB from quite a while ago somebody else had used this setup successfully so that seems my best shot at the moment.

A post was split to a new topic: Fritzbox 4040 use WAN port as LAN

Hey folks! I have a weird issue with freshly bought 4040. I'm on the latest stable (21.02.1). I have 1gbps uplink connected to the fritzbox. When I connect my laptop with ethernet to the ethernet switch port, my download speed is around 850-900 Mbps - pretty impressive. Still, when I connect through 5 GHz ac wifi, the speed in the same test drops to ~300 Mbps. I've already installed irqbalanced, what else might be causing such a huge gap between wired and wireless speed? The same laptop (and other clients) easily reach > 500 Mbps on my old AP.