Renew IP lease
A DHCP client can on occasion send information in DHCP requests: hostname, MAC address, operating system, and DHCP version. All operating systems provide their most recent IP address to the DHCP server. If you change your MAC address to minimise risk, best to also renew the IP leases on the router.
Go to Apple menu -> System Preferences -> Network.
In the list on the left, select the network service that needs a renewed IP address.
Click Advanced, click TCP/IP, then click Renew DHCP Lease.