When running neptune3 and the companion-app from within the installation folder of the installer, changing the connection settings of the companion-app can have side effects.

By default the server.conf in the installation folder is used for the servers to know which IP and port they should be listen on.

When the companion-app is run in the same folder this server.conf is overwritten once it tries to connect to a remote server (e.g. on a NUC). As the server.conf is then overwritten with the IP and port for the remote server a fresh start of neptune3 and it's servers can't listen on these IP / port settings and will fail, which means no simulation works for these services.

A proper fix is to use a different conf for the companion app by setting the SERVER_CONF_PATH environment variable to a temp location and write the settings file there.