It will be some trivial setting in the end, but need more information to pin it down.
For example if I do ipconfig on this PC this is what I get
Host Name ........................: greypc
Primary Dns Suffix ..............:
Node Type ........................: Unknown
IP Routing Enabled................: No
WINS Proxy Enabled................: No
Ethernet adapter Local Area Connection:
Description ......................: SiS 900-Based PCI Fast Ethernet Adter
Physical Address..................: 00-01-CC-DE-C0-D0
Dhcp Enabled......................: Yes
Autoconfiguration Enabled ........: Yes
IP Address..........................: 192.168.1.30
Subnet Mask ......................: 255.255.255.0
Default Gateway ..................:192.168.1.254
DHCP Server ......................: 192.168.1.254
DNS Servers ......................: 192.168.1.254
Lease Obtained....................:16 March 2008 14:42:25
Lease Expires ....................: 19 January 2038 03:14:07
Yours will say Wireless adapter not ethernet and will be a different model.
Hostname is just the name of the computer, but it needs to have one.
Default Gateway, DHCP Server and DNS Servers are all the same IP number because that's just the IP of the router.
IP address has the same first three numbers, but the last number (30 in this case) distinguishes this PC from any others on the network.