Using treats is very effective if you do training sessions. Their regular food is great to use for training if your dog likes eating (food oriented) some dogs like toys better than food.
The trick is to distract them with a pleasant activity then ring the bell while they are distracted so that they relate the food/playing to the sound of the doorbell, then praise them for ignoring the bell. I like to do it away from the door to give them room to mess up at first, toss some food in the floor then rush towards the front door, he might look up at you or even follow you, ignore him, ring the bell and then correct him by telling him to go back. Place him back away from the door give him some food and try again. Praise him at the sigh of improvement after each exercise. Do sessions of 4 or 5.
Modify slightly as needed depending on the reaction. Training also works with knocking.
Whenever you are trying to change a behavior it will take time and perseverance. All dogs are different in the way they learn and not all training techniques work for all trainers/owners.
Also remember that most times the more time you spend correcting him when someone is at the door the more he will get riled up. If the above training worked for you keep a small bowl of food in an easy access location to toss in the floor on your way to getting the door. Stay happy and pleasant.
Doing other training like making sure your dog is in their bed when you leave the house helps with correction the barking too since it enforces that the human does not intend for the dog to protect the house.