Multi-access edge computing (MEC), deploying cloud infrastructures proximate to end-devices and reducing latency, takes pivotal roles for mission-critical services such as smart grids, self-driving cars, and healthcare. Ensuring fault-tolerance is paramount for mission-critical services, as failures in these services can lead to fatal accidents and blackouts. However, the distributed nature of MEC architectures makes them more susceptible to failures than traditional cloud systems. Existing research in this field has focused on enhancing robustness to prevent failures in MEC systems rather than restoring them from failure conditions. To bridge this gap, we introduce Fatriot, a SmartNIC-based architecture designed to ensure fault-tolerance in MEC systems. Fatriot actively monitors for anomalies on MEC hosts and seamlessly redirects incoming service traffic to backup hosts upon detecting failures. Operating as a stand-alone solution on a SmartNIC, Fatriot guarantees the continuous operation of its fault-tolerance mechanism, even during severe errors (e.g., kernel failure) on the MEC host, maintaining uninterrupted service in mission-critical services. Our prototype of Fatriot, implemented on the NetFPGA-SUME, demonstrates effective mitigation of various failure scenarios, achieving this with minimal overhead to services (less than 1%).