On your windows server computer, type in ipconfig at the command prompt and press enter. You should see info about the computer. The below is what I get on my computer. The default gateway is the netgear router, and the IPv4 address is the lan ip address of the computer.
Wireless LAN adapter Wireless Network Connection 2:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::eda8:a9dd:bd47:fc09%13
IPv4 Address. . . . . . . . . . . : 192.168.1.2
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1