Look into the concept of a 'serial server' device and see if that will help. It creates a network enabled serial port.
I'm currently using a QuaTech serial server to speak to my remote Arduino on my home network. It create a COM port. I paid about $15 for this on Ebay. Other people have used print servers like Lantronix EPS1, but this requires quite a bit more fiddling to get going.
You can also find software under Windows & Linux that allows a dedicated spare PC to create and maintain a internet/intranet COM port. The serial server is a dedicated device.
I had it running within 5 minutes of unpacking it, and can now see serial i/o and load my Arduino sketches remotely.