A network access control system includes a communication device and an authorization system. The communication device is configured to communicate time-critical messages through a time-sensitive network during scheduled time windows. The communication device is further configured to be communicatively connected to a candidate device and to receive a network access request from the candidate device while blocking the candidate device from communicating through the time-sensitive network. The authorization system is communicatively connected to the communication device and configured to authorize the candidate device via a multi-factor authentication protocol that requires a user of the candidate device to successfully provide multiple identification factors. In response to the authorization system authorizing the candidate device, the communication device is configured to grant the candidate device restricted access to one or more of send or receive approved messages through the time-sensitive network.