Samsung Galaxy S5 — Often only Edge data speed after daughterboard replace

Hi there Android-community,

a few month ago, i dropped my phone on hard floor and crushed my display.

So i got a repair kit with new display and new daughterboard. Now after replacing the parts. Everything works fine except the mobile data speed.
Most of the time i only habe Edge speed.
WLAN, Bluebooth and voicecalls work with no problems.

But this slow internet connection is annoying. Also sometimes i have complete network DCs.

First i thoght ok so the antenna is broken. But at some locations like the gym i work out i have constant H+ speed.

I also replaced the antenna cables without any improvement of connection...

Perhaps somebody can help. Greetings Max

Nobody any advice? =(