This sounds like a strange problem you're experiencing with your vehicle. It could potentially be an issue with the glow plug relay or the wiring connected to it. The relay is responsible for sending power to the glow plugs, so if it's not functioning properly, the glow plugs may not be receiving the necessary power to heat up and start the engine.
It is also possible that the issue is with the starter motor, which may be having trouble turning over on a cold morning. This could be caused by a variety of factors, such as a weak battery or a problem with the starter solenoid.
It would be best to have the vehicle inspected by a professional mechanic, they will be able to run diagnostics and diagnose the problem more accurately. It's also recommended to check the wiring and connections to the starter, battery, and glow plugs, as well as the starter motor itself, to make sure they are all in good working condition.
It's worth mentioning that sometimes, the problem could be related to the engine oil viscosity in cold temperatures, that can make it harder for the starter motor to turn over. Make sure to use the recommended oil viscosity for your vehicle and the temperatures in your area, and check the oil level as well.
It's also important to note that the Nissan Patrol is known for its durability and longevity, even with high mileage, so it's possible that with the right diagnosis and repairs, your vehicle will be back on the road running smoothly.