firewall blocking a ip address outside my subnet

Hi,

I’ve got Symantec endpoint protection, and today I, and all of my collegues, got a pop up saying its blocking an ip address. My local ip net is 192.168.0.1-255, but this is from the ip address 192.168.1.1 ( remote host and local host 192.168.1.255 ) In the symantec log it shows the mac address, but I dont know where to start, or what to do?