Dear Helen,
Your detailed explanation of how the Firebird client/server system
works was very valuable.
Most importantly, the example path you have provided:

> MAINSERVER/3051:C:\Data\databasename.fdb

was the answer I was looking for: it solved all the problems with the
connection to the SBS server. Thank you so much !

You have questioned the use of non-standard port 3051. I know that the
standard port is 3050, however long time ago I was advised to use a
different port 3051 to avoid problems with an Interbase server and/or
other older version of Firebird running on the same machine?
Is it valid to use different port in these particular cases, or is it
irrelevant ?

What are the true reasons for using different listening port ?

If I was going to use the standard port 3050, would it be still
necessary to provide the /3050 switch after the server name, or does
it become redundant ?

Thank you once again for your great help - most appreciated.

Kindest regards,
Mario