My server-to-server TCP/IP connections are not working.

First check that the basic XDB Server installation is functioning for each XDB Server by itself. If you have problems making a server-to-server connection, try connecting the client directly with each XDB Server (using the same protocol) and observe what happens. Also, if one protocol does not work for a particular connection, then try another one (if available).
Ensure that xdbnet.ini is built and present on your XDB Server machine.
Insert a single letter T (for TCP/IP) in the LINKATTR column of your SYSIBM.SYSLOCATIONS table. This single character value determines which address information in xdbnet.ini is used for the connection.