I have the same Problem.
Under ssh i can establish a connection if i just use "moonlight" as a command. But if i paste the command used by the es-ui i get the following error:
Command: # python /usr/lib/python2.7/site-packages/configgen/emulatorlauncher.pyc -p1index 0 -p1guid 050000007e0500000920000001000000 -p1name "Pro Controller" -p1nbaxes 4 -p1devicepath /dev/input/event0 -system moonlight -rom /recalbox/share/roms/moonlight/1088017781_.moonlight -emulator default -core default -ratio auto
Traceback (most recent call last):
File "usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py", line 268, in <module>
exitcode = main(args)
File "usr/lib/python2.7/site-packages/configgen/emulatorlauncher.py", line 182, in main
command = generators[system.config['emulator']].generate(system, args.rom, playersControllers)
File "/usr/lib/python2.7/site-packages/configgen/generators/moonlight/moonlightGenerator.py", line 15, in generate
configFile = controllersConfig.generateSDLGameDBAllControllers(playersControllers, outputFile)
AttributeError: 'module' object has no attribute 'generateSDLGameDBAllControllers'
So the log shows me:
[2019/04/20 22:19:32.494] (WARN!) : ...launch terminated with nonzero exit code 256!