The OpenEdge Hive

First thing first -> ProEnv is just a shell environment that sets
the environment variables, such as DLC (pointing to the Progress/OpenEdge installation directory)
and adds it to the %PATH% ( %DLC% and %DLC%\bin ).

Second, Progress/OpenEdge database includes several processes that altogether
enable client connections. The first one that starts is called database broker process (_mprosrv.exe).
The -S parameters specifies the db broker's tcp listening port number (or service name
that maps to the port number).
On the first client connection (to the port 3200 in your case), broker spawns additional
process called remote server (also _mprosrv.exe).
Parameter -Mn says to broker what is the maximum of the remote servers it is allowed to start.
Parameter -Ma says how many client connections one remote server can accommodate.
-Mi commands the minimum number of client connections on remote server
before broker spawns additional remote server.
-n denotes total number of all connections to the database: that includes all
local connections and all remote connections.
-Mpb and -ServerType (4GL btw and not ABL as you wrote) - you need them only if you wan't to start
additional broker for e.g. SQL-92 connections (with its own pool of remote servers - in the
case of SQL-92 these are _sqlsrv2.exe executables). See:
http://progress.atgnow.com/esprogress/Group.jsp?bgroup=progress&id=P7843

In your case, -n is set to low as it must be : -n > (-Ma * Mn)

So it should be enough to do on the server:
proenv> proserve MyDb -H ServerIp -S ServerPort -n 26 -Mn 5 -Ma 5
and on the client:
proenv> prowin32 MyDb -H ServerIp -S ServerPort

Hope this helps,
Sasha