I don’t know about your setup and other client connecting to the database. However in loraserver.toml (and lora-app-server.toml) you will find the following configuration in the postgresql section:
# Max open connections.
#
# This sets the max. number of open connections that are allowed in the
# PostgreSQL connection pool (0 = unlimited).
max_open_connections=0
# Max idle connections.
#
# This sets the max. number of idle connections in the PostgreSQL connection
# pool (0 = no idle connections are retained).
max_idle_connections=2