ON ESXi 7, AQC111u based card is showing and working at 1G speed when in "Auto" mode while at PHY layer, it connects to the switch at 5G speed.
The dropdown for manually switching the speed only showing up to 1000 speeds. If you force port speed to 2500 on the switch side, ESXi UI show link speed as 2500 and it works faster than when connected at 5G speed.
Could you please update AQC111u driver in the package? Synology works fine with Linux driver and the same adapter.