Dude, for serial connection, FLOW CONTROL= XonXoff, NOT the Hardware option, its in the manual
You should get the prompt now where you can run 'QUICKVC' etc.

I have the same Router so let me know if there's anything else..

p.s - the IP address should be 192.168.200.254 sm 255.255.255.0 as stated by Shah.. you havent mentioned if you tried this IP address in a browser to manage the box - did it work?

You should be good to go..