There is an issue in Mac OS 10.7 when working with Workgroup Manager (WGM) to administer a Mac OS 10.6.8 or other legacy directory service. After launching and quitting WGM several times you get an error reporting “The server you are attempting to connect to has the maximum number of connections allowed.”
The issue is a daemon “dspluginhelperd”. You can either quit the process in activity monitor or run the command in terminal:
sudo killall dspluginhelperd
After this you will be able to launch Workgroup Manager and connect to your directory servers.