PortForwarding

I've been trying to portforward so i can host a server. I've done it before with this router but now for some reason my device doesn't pop up when i go to the applications list to portforward. it used to pop up. 

when i go to my device list i can see that my computer pops up. and for some reason there's 2 of my PC's, one with an older ipv4 address and one with my current ipv4 address. but the one with my current address doesnt show up in the devices that i can portforward. PLEASE HELP. THIS HAS BEEN DRIVING ME CRAZYdevice i need to show upmy pc doesnt show up at all