Since RUT955 sends NMEA data over IP/Hostname you can't directly read that over serial port, BUT there is workaround for this problem:
Services > GPS > NMEA configuration:
Hostname: [<routers own IP>, e.g. 192.168.1.1]
Port: [Port of yours choice]
Protocol: [TCP/UDP] *doesnt really matter just choose the same everywhere
NMEA sentence settings: choose what you need
Services > RS232/RS485 RS232 tab settings:
Baud rate / Data bits / Parity / Stop bits / Flow control: [choose what you need or leave on default]
Serial type: [Over IP]
Protocol: [Same as GPS settings]
TCP Port: [Same as in GPS settings]
After configuring that, connect your console with RS232 through correct COM port and Baud rate, and you should see GPS data flow in yours terminal.
Basically what you do is: Make router transmit GPS data to server, which is same router, and then make server transmit received data to Serial port.