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.

1 Like

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: