Hello,
thnaks for the advises.
I will power the strip from both sides in the future... actually the TV is mounted to the wall and hard to dismount for me alone..
As the problem with disconnects and flickering stays i tried to use the SPI port on my Raspberry Pi.
And it works completly without any issues!
The lag is reduced to a very calm minimum and i have no Problems with flickering or disconnects or anything.
I used a DuPont Cable (20cm) wihtout resistor or capacitor direct to the Dataline on the Strip and it works great.
Just had to change the RGB-order in Expert Settings.
The only little problem is that in Standby-patternit flickers sometimes. But maybe this is due to my very cheap noname SD-Card.
For example, when using the Pac-Man-pattern sometime half of the strip flickers. But not everytime and if using Videocapture it works flawless.
So good enough for me! Thanks for the help out here.