Hot end auto-tuning failed due

[resam]

cheap E3D v6 clone with 24V 40W heater and old-style thermistor glass bead.
M305 P1 S"Hotend" R4700 T100000 B4725 C0.0000000706

The original wires of the thermistor are about 10cm long, and then plug into a 2-pin dupont connector on a small PCB. From there it goes over a CAT5e+RJ45 cable to the Duet, about 70cm away. I think read somewhere that connectors/plugs might influence the thermistor measurement, but I don't remember for which type this was a concern...?

[dc42]

@resam, please check that the thermistor connections are well-insulated from the hot end metalwork. Shorts between the leads of that type of thermistor and the heater block are common.