How Do I Get My Mitm Attack to Work?

Hi! I'm Cameron. I have recently been having many issues with kali linux trying to get my man in the middle attacks to work. I have tried arpspoofing with ettercap but every time I set up the attack, my target computer's connection to any websites gets cut off. It just keeps loading. How do I get my attacks to actually sniff instead of kill the connections? Thanks, Cameron.