I'm having some issues when connecting to the printer via USB, see Wanhao i3 PLUS restarts when connecting USB.
After some research I thought I would try to remove the
auto-reboot jumper. Now that the i3 Plus uses a custom board instead of the standard Melzi, I'm not sure where to find it.
See pictures attached:
The pictures don't help much, and I don't know the board. But if it is as described here, Elec Freaks Wiki - RAMPS Melzi, then you need to look for the FTDI Chip FT232. The reset is caused by the DTR Signal. There needs to be a copper trace from pin 2 to the capacitor and then to the jumper. From the jumper a trace leads to pin 4 of the Atmel ATmega.
If it is a clone, the jumper might have been "optimized away". If so, desoldering the capacitor gives the same result. Be certain to desolder the right one. If unsure keep the capacitor and solder it back in if it was the wrong one.