Assuming you are wanting to set a static IP for the XEP, the IP you select should be any address on your subnet that isn't part of a DHCP range. the default gateway IP should typically be your home router. So, if you have a router at 192.168.10.1, you would enter that as the default gateway. Since your router is probably configured to provide DHCP addresses starting at the low end, I would use something like 192.168.10.225 for the XEP. Technically, you should configure your router to never give out DHCP addresses that overlap your statics, but that is unlikely to happen in a home environment.