port forwarding wrong ip

Hi, I have seen this asked before but not really resolved. So I set up port forwarding for a PC that I use for my camera system. The forwarding stopped working and I now see that the IP address that I set that ends in .54 shows in the Xfinity app  saying  reserved ip address ends in .53 so it does not match and it does not work, Calling Xfinity yielded NO help.  HELP?  Thanks, Adam