UR22 mk2 through Jack (Linux)

I need help to set up my UR22 mk2 through Jack.
Linux and Ardour are a wonderful way to use the interface but there is the Issue, that I can’t really separate the inputs to be Mono. On the Windows driver you can literally just click one button but here it’s different, as Steinberg doesn’t really care about open source supporters.
Nevertheless, I can kinda solve my problem through my DAW in ALSA but it requires plugging around for every track, which is quite annoying and it isn’t even real Mono, as I just double the Input.
Now I try to work on a Jack Server, which should make my goal happen but it’s sadly only detecting one Input. Does anyone know what to do? I’m at all just a beginner with Jack, so I can’t even get my system through yet.^^