Up and downs with the FRITZBox 6490 Cable

This issue might be only useful for people living in Germany. My internet provider is UnityMedia and for some time now users are able to use the router they want and do not have to rely on the on by UM – a hard to work with Technicolor router. I had my problems with the router as well:

  • It has 2,4 and 5 Ghz support but not in dual mode
  • Port Forwarding is a real hassle
  • It looses connection without any apparent reason

So it has plenty of reasons to switch to another one. I always liked the ones by Fritz! and so I looked into buying the 6490 cable version. But it is 250 € new and 110-150€ used. So a scrimper as I am I bought a used one on a german “craigs list” and got it for incredible 50€.

But then I discovered that it is difficult to reuse a device that somebody else already registered with UM. BUT – for me it worked. I had to convince the person in the service hotline to try it anyway and surprisingly for her it worked! I cannot promise anything for people buying used ones as well – but there is hope.

Then there came the down

Ok so I got the router, registered it with UM, changed some settings and then: I had the glorious idea to try to remove the KDG branding that was on it by logging into the Adam2 FTP account and change the firmware_version env to the avm firmware. But careful: Since there apparently no avm firmware available on the device it will get stuck into a bootloop. 

The solution: So what this post is actually about! I tried hard to get back onto the box and try to change it back

  • Regular FTP did not work
  • Safety Access IP via did not work
  • Safety Access IP via did not work

But, if you have the same problem, try using the firmware recovery of the Fritzbox 7390. This will of course not be able to recover anything but it will lead you with an IP that you can use to access the system again. Just FTP to the IP the recovery tool gives you.



Creating Windows 10 User Accounts after Upgrade

Apparently there is a problem with upgraded Windows 10 systems which has a corrupted default user file. Creating a new user works fine but a logon leads to a “User cannot be loaded” Error.

Windows tries to create the new user profile by copying the necessary files from the default profile (which is corrupted) and fails doing so.

This can be solved by overwriting the Default Users’ NTUSER.DAT under C:/Users/default as shown in other tutorials. My Problem was to obtain a non-corrupted user file.
So to help everyone with the same problem, one can find an working default user file HERE!


Repetico Flashcards

I am currently preparing for several exams this semester and I am using a flashcard service, called “Repetico”, for the first time. I am using it to help me prepare on three modules which a high amount of slide and a wide variety of subjects which must be learned by heart. The modules are:

Up until now I am happy with the solution even though the final success of this study approach will only be judged after my exam result.

But for now everybody that has the same modules can apply for learning with those flashcard sets. You can write an request by clicking on the links above.
Maybe it helps some of you as well.

Please not that I am not solely relying on those cards especially because there are a lot of exercise on those topics, but rather to know definitions, principals or procedures.
Especially in distributed systems and Infovis it is crucial to know the protocols, procedures, algorithms and to have created so lattices, serialization-graphs and visualizations by hand.