You will want to set that up in the Channel configuration area of the controller folder.  The controller properties area sets up your pc communication with the PLC.  When you changed that, you changed the address that your PC was using to connect with the PLC.  Change the node in the channel configuration and download.  If that is the channel you are using to communicate with your PLC (sounds like it must be) then you will be prompted as to whether you really want to change the communication properties on the PLC or not.  Select that you do want to make that change.  You will then lose communications with the PLC - expect this.  Now go to the controller properties and set it up with the new communication parameters that you just set up the PLC to have and you should be able to go back online.