cannot add a port forward on TCP 1802

I have a RAX75 router and it has the latest firmware available. It was recently reset and now I cannot add a port forward for Fantasy Grounds server (TCP port 1802). When I attempt to add the port forward, the router reports that the forward conflicts and to disable UPnP, Remote Management, etc. I went through the router and checked everything and I cannot find anything that could be conflicting. I had this setup prior to the firmward update and it has been working for months but now it won't work. I need some assistance!