How do I get my potty trained dog to stop peeing in the house?

My 7ish year old neutered male Shihpoo is potty trained and knows he shouldn’t pee in the house. However, when someone comes to the door, or he sees a dog walking by, he loses it and runs to the wall in our entryway and lifts his leg and pees. We have tried crating him, but he literally sounds like he’s about to have a heart attack.

I have no idea what to do to get him to stop.

We have tried dog diapers, but he can take them off.

Help