Apache Guacamole is a clientless remote desktop gateway. It supports standard protocols like VNC, RDP, and SSH.
Nethserver-guacamole tries to guess the right settings.
For custom ldap encryption (none, ssl or starttls):
config setprop guacd Encryption none
For use a custom ldap port (usually 389 or 636):
config setprop guacd ldapPort 389
For changing the LDAP username attribute:
config setprop guacd usernameAttribute displayname
https://community.nethserver.org/t/howto-install-guacamole/9047