Most of us know that when troubleshooting connection problems to a server, a great tool is the "Trace" option in User preferences // Ports. What many don't know is that you can take it one step further. It is possible to specify the exact port you want to troubleshoot by adding the port name and three exclamation marks (!!!) in front of the name of the server name you want to test.
For example, suppose users are having trouble hitting the LN00 server. You have TCPIP and SPX both enabled, but suspect its an SPX problem. On the trace, instead of entering just the server name to trace, enter
for example SPX!!!LN00. You'll be able to test just SPX connectivity.