open CMD prompt type in ipconfig release all then ipconfig renew this will change the local ip of your PC so long as it is not bound to the mac in your router settings, if you want to change your modems ip and your ISP uses dynamic ips you can either plug striaght into to the modem with a pc and run ipconfig release/renew to try and get a new ip or you can unplug the modem for 30min-8Hours and see if another modem on your node gets handed your now unleased ip which would mean you will be handed a new one when you come back online with the modem by your ISP.