The Commodore A2065 Ethernet Network card has only AUI and BNC connections as RJ45 UTP were not common in that era. A transceiver from AUI to RJ45 is a solution for this, resulting in approx. 5 Mbit/s. I have this network card in my Amiga 4000.
I was surprised with the speed of the A2065 with a transceiver. The maximum theoretical speed is 5 Mbit/s while I was manage to get 599 KB/s which is approx. 4.8 Mbit/s. I used tcpspeed and the roadshow TCP/IP stack. It also does well the DNS requests.