DIAGNOSIS This is almost always an overheating safety cut-off. The unit's vents are blocked or the internal temperature is too high.
FIX Move the oven immediately. It needs at least 5 inches of clearance on all sides, especially the back and top where the exhaust vents are. Clear anything above it. Vacuum the rear vent grille to remove dust and grease buildup.
IF THAT DIDN'T WORK If ventilation is clear, the thermal fuse or high-limit thermostat may be failing intermittently. These are safety devices on the heating element pathway. They require component-level testing with a multimeter.
HEADS UP This is a critical safety function. Do not bypass it. Persistent shutdowns with proper ventilation indicate an internal fault requiring professional repair. Continued use risks a fire.