i had left the mac in sleep mode and when i returned and woke it up there was an alert message stating that someone else was connected to my ip address. no-one else in the house was using a remote device or using wifi connection. is this cause for concern and how do i find out if my security has been breached.
Your security has not been breached. Nothing was done to your computer at all.
Some other computer or device on your network was given the IP address that your computer used to have, because when your computer went to sleep, it stopped using that IP address. That's all.