100TX only with Mausi 2.20

Hey there,

my Mainboard is an Asus ROG Maximus VIII Hero Gaming and I'm using IntelMausiEthernet.kext in Version 2.20 which seems to be the latest (stable at least).

I only happen to see 100TX sync with my Ubiquiti unifi switch. Any idea what's going wrong? I already tried disabling auto negotiation and set it to 1000T fixed but then it doesn't sync again.

Any help is appreciated.