Loading 3C5X9 re-entrantly

The IPX and TCP stacks bind to the first logical board they find. You cannot load the IPX and TCPIP protocols to multiple boards in DOS. On a network analyzer you will find that IPXODI and TCP communicate over the first board they find.

A way around this is to only load the appropriate frames to the boards:

LINK DRIVER 3C5X9
PORT 300
FRAME ETHERNET_802.3
PROTOCOL IPX 0 ETHERNET_802.3

LINK DRIVER 3C5X9
PORT 200
FRAME ETHERNET_II
PROTOCOL TCPIP 8137 ETHERNET_II

When the protocols are loaded, they bind to the correct adapters.

In your setup, watch the board numbers assigned to each adapter. These are the logical adapter numbers created by the multiple frames loaded. When you load the 3C5X9.COM driver the first time, it reports
BOARD 1, FRAME ETHERNET_802.3
BOARD 2, FRAME ETHERNET_II

On the second load of the .COM driver, you will see:
BOARD 3, FRAME ETHERNET_802.3
BOARD 4, FRAME ETHERNET_II

When you load the IPXODI driver, you will see that it bound to the logical BOARD 1, or the first adapter. When you load TCPIP you can see that it used BOARD NUMBER: 2.

This shows that logical board 3 and 4 (or the second adapter) are not being used, and since in DOS you cannot re-load the IPXODI stack it will always only work on the selected adapter.

With the above NET.CFG fragment, the fist board loads as logical 1 and the second as logical 2, IPX and TCPIP will then be bound to the correct adapters.