SMB Share too slow

Well … I could live with 50 MB/s but not with 20 MB/s…
I wanted to use a newer SAMBA Version in an LXC Container, but with the above config i can’t get the usb device recognized inside the container…
//Edit: I finally got the LXC Container/Samba setup running (suing this guide), but the speed is the same as before. what else could i try? 20 MB/s is just …