Copied the network tables to localhost. Now pgRoutingLayer will not show the connection under "Database" anymore. What am I missing? The username and password is saved in QGIS under the localhost connection, so it's not that.
Database connection established. Turned out the pg Routing extension was not properly run in pgAdmin 4 (the database). Instead of using the GUI,
Database --> Create --> Extension
the extension had to be run in the following SQL query format:
CREATE EXTENSION pgrouting; SELECT pgr_version();