Compaq 247320-003 - Deskpro 4000 - 5166 Model 2500/CDS Reference Manual page 206

The RJ-45 and the AUI connectors require different cables.
Following are the specifications for the cable required for each
type of connector.
The RJ-45 connection uses an unshielded twisted pair (UTP)
cable of 22, 24, or 26 gauge. The cable must comply with the
IEEE 802.3 10BASE-T standard.
Category 3 cable is rated to 16 MHz and is used for 10
Base-T operation.
Category 5 cable is rated to 100 MHz and is required for
100 Base-TX operation.
The maximum distance between the computer and the hub, for
both categories of UTP cable, is 100 meters.
The AUI connection uses the standard transceiver cable or AUI
cable conforming to the IEEE 802.3 10BASE-5 specification.
The maximum distance between the computer and the hub on
the thick Ethernet cable is 50 meters.