There is a high chance that your NTC is simply broken (or the wiring has defects).
The pull-up setting depends on the hardware and is in no way suited to tune your readings.
If I read the schematic correctly, then this board has a 4K7 pull-up, so this is the only correct value.
Use Generic 3950 sensor type (no need to specify a pull-up, 4K7 is default). IF it is really a 100K NTC AND IF it is correctly wired to the correct port AND IF you have the correct pin (PC4 is THERMO0) THEN you should have approximately valid readings.
In any other case, you are having a different issue that surely cannot be remedied by defining a custom temperature curve or pull-up