I'm deeply sorrow for not able to speak German but I'm learning.
I'm software developer and the internet connection is crucial for my job.

I was using Vodafone couple of months ago, I had stabilization issues so the guy in Telekom support suggested to switch Telekom for "Better" support.

So I'm using Telekom for 2/3 months, I still have stabilization issue. I attached router logs in this post.

If you check the logs, you will see one specific one explain the situation.
(R006-1) DSL antwortet nicht mehr (erfolgreiche DSL-Synchronisierung wurde verloren).

First approach from Telekom side was "Your router is old", I rent brand new from Telekom (Speed Port 4).
Nothing changed except I'm going to pay router rental.

They send technical to fix this issue, He changed only cabel positions and he didn't find any issue.
Then, I waited couple of days for making observation. Nothing changed, literally nothing.

After contacting with Telekom technical person, They said "No problem exists in your internet".
The question what should I do next?