I noticed you call this 'ethernet/ip' but it actually is not. Its just a DF1 serial connection 'cheating' by going through ethernet instead of a serial cable. So a few questions:
Are you using the DF-1 serial driver on both ends (Crimson and RSLinx)?
What Virtual Serial Port (VSP) software are you using on the receiving end (is it a brand suggested by Red Lion)?
What TCP Port did you assign in Crimson?
And what TCP port did you assign in your VSP software?
What COM port did your VSP software assign?
Did you verify your VSP com port is not in use by something else?
Have you tried temporarily shutting off your firewall just in case it is blocking the TCP port you selected?
How did you wire your RS-232 cable between the Red Lion and the SLC (a little tricky, if I recall. Carefully follow the Red Lion documentation). Getting that Red Lion RS232 RJ11 connector wired is a bear, IMHO. And it is so easy to get the pin2/pin3 swap wrong on the SLC end.
Getting a virtual serial connection set up is an exercise in getting a lot of details just right. Definitely worth double checking the details above. It sure is great once it works