I’ve solved the problem! Now I can use upto 2.5mt of I2C and 1-Wire also… the problem (in my case) was that, using a grove shield (obviously), two digital I/O are coupled on the same cable and connector, so I’ve used the caution to use only one I/O per cable in the software.
Now can use both flat wire and silicon jacket twisted cable, the junction are welded and protected with a heat shrink tube.