Abstract Time‐Sensitive Networking (TSN) extends IEEE 802.1 Ethernet for safety‐critical and real‐time applications in several areas, for example, automotive, aerospace or industrial automation. However, many of these systems also have stringent security requirements, and security attacks may impair safety. Given a TSN‐based distributed architecture, a set of applications with tasks and messages as well as a set of security and redundancy requirements, the authors are interested to synthesise a system configuration such that the real‐time, safety and security requirements are upheld. The Timed Efficient Stream Loss‐Tolerant Authentication (TESLA) low‐resource multicast authentication protocol is used to guarantee the security requirements and redundant disjunct message routes to tolerate link failures. The authors consider that tasks are dispatched using a static cyclic schedule table and that the messages use the time‐sensitive traffic class in TSN, which relies on schedule tables (called Gate Control Lists, GCLs) in the network switches. A configuration consists of the schedule tables for tasks as well as the disjoint routes and GCLs for messages. A Constraint Programing‐based formulation, which can be used to find an optimal solution with respect to the cost function, is proposed. Additionally, a Simulated Annealing‐based metaheuristic, which can find good solution for large test cases, is proposed. The authors evaluate both approaches on several test cases.