Networking for Apple DOS cards and OS9.1

For a long time I had been unable to network my 12" 100MHz Apple PC Comp. Card with OS 9.1, while it worked with 8.1. My card is inside PowerMac8600. I had PC Setup 1.6.4 and 2.1.7 with no success. I patched PC Network Extension 1.6.4 to work with highr OS systems. PC side worked fine, but it could not network properly. I came across a solution purely by accident. I will not describe how here, but I will give yo the solution that worked for me. It works with PC Setup 1.6.4 which I use. It will probably work with 2.1.7. The solution is to reduce the MaxMTU (on PC side) for your connection to less than the default (1500 bytes). I use 1320, although I it may work with higher values. MTU (Maximum Transmission Unit)is a TCP/IP parameter stored in the windows registry. More info can be found in www.dslreports.com. To add or change this registry item download DrTCP from the above website, or edit the registry key (for W98):
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\NetTrans\002
add a new string value called "MaxMTU" and set its value to 1320. Make sure first that the 002 key above corresponds to the PC Network Adapter. You can recognize it by the IP number which should match that assigned to the adapter as seen in WINIPCFG.
It worked wonders for me. Not only made the neworking work, but eliminated many crashed I had experienced with OS9.1 on the PC side.