What I understand :
cura 4.0 has many options under machine settings -> for the parameter: "g-code flavor" e.g. ultimaker , reprap , marlin
RepetierServer has only a few under Firmware : e.g. marlin , reprap
Both settings must be equal , so UM2+ starts printing .
I tested both values "marlin" and "reprap" cura 4.0 . the result is UM2+ starts printing but the filament gets entangled.
the filament wraps around the nozzle.
the same file sliced with g-code "ulitmaker" and saved on SD card works fine
Which option/parameter did you choose for Cura and Repetier so that the result is the same like I'm just working with the SD card ?
And what is the startcode so that the filament comes out of the nozzle already before ? when you chosse g-code marlin/reprap you have to put the code in the startcript, when you choose ultimaker in the g-code the UM2+ Firmware will do ist for you