You've done everything necessary to achieve proper temperature.

The fan clutch won't solve a problem of 105°C. It's just getting fully coupled at that temp. M/B thinks that 105°C. is perfectly acceptable.

So, my suggestions are as follows:

1) Borrow an infrared temp sensor and confirm the gauge is accurate. I'm betting that it's fine, but, you never know.

2) Pull the radiator and thorougly clean the condenser if this has never been done. It's surprising how much debris can accumulate in the unit and restrict the airflow. You need to use a compressor, a pressure washer, some condenser cleaner, or a combination of all three for a successful result. You should be working from the rear and forcing water/air/solution forward toward the front. You can't do this with the radiator in the vehicle.