He's Only Agressive at Home

Hey all,

We recently adopted a 2 year old Newfoundland (3 now), Max, and we're having a very specific problem. Max is usually an amazingly well behaved dog. We take him to dog parks where he gets along well with other dogs, he's remarkably well leash-trained and doesn't even bark at the yappers going crazy on their lines when we walk him by. But at home, on the deck, when deliveries are made or people come over he is an absolute MENACE. I mean full aggression mode, barking, snarling, lunging. He's never bitten anyone, but I'm not sure if he ever would or not.

I understand that dogs can be very territorial and protective, but this feels next level. I've never dealt with this kind of behavior before. We've tried talking him through it, using a clicker to distract him, literally holding onto him. One time my wife had to full on tackle him to the ground because no one noticed someone was approaching the deck. He isn't a danger to any of the family during these times, even when he was tackled he was surprisingly gentle trying to wiggle away. But the behavior clearly isn't acceptable and he's being SO stubborn. We don't want to just put him inside when people are coming to the deck because that's just ignoring the problem rather than trying to fix it. We've taught him commands so it isn't like he just doesn't want to listen, he is usually as gentle as can be so it isn't an overall personality thing, we've trained him with a clicker and he usually comes when called so it isn’t him not understanding.

Any advice on how to go about training him would be helpful. We're ready to try just about anything.