Unfortunately I don't know how you get manjaro to connect to a serial port, but I'll try to be helpful anyway.
First I think you should change the subject to something along the lines of "How do I access a RS232 serial port in manjaro?".
Secondly you might wan't to tell people that your old Dell D630 Latitude has an old school RS323 serial port on the back and you need to terminal at 9600,n,8,1 into the console port of a cisco router in order to configure the router.
I'm working on my CCNA too, so I can guess what you're trying to do, but to other people it might not be that clear so why not stick to asking about getting a RS232 port to work in manjaro or maybe wine, more people might relate to that.
Sorry I can't be of more help, I've got an ancient Dell laptop too specifically for setting up routers, but I've kept it running windows xp and putty - it's the only thing I use it for so I haven't gotten around to changing the OS.