In case you need to run the lab session without the internet, there is a workaround using a local server in the school, but it has some limitations.
Prerequisites:
TNServer installation in the school (can run on school hardware too).
Internet connectivity to TNServer is required (for it to sync student data, and course resources). Lab systems to be connected with TNServer via LAN.
NextLab desktop application to be installed in all the lab systems.
Limitations:
Exercises based on learning tools will not work
Auto evaluation may not work for all exercises.
Here, you will not be able to schedule a session in advance. You can start the session for a given class-section and chapter at the start of your lab session.