I have free range chickens and a neighbor with a curious dog. 2 years ago their dog attacked and killed 3 of our chickens, our solution, my husband went over there and threatened to shoot his dog right off his deck if he didn't control his dog. 2 years later, haven't seen that dog on our property since. Yes it was threatening and he was willing to do it, he had his gun in hand when he went over there. But it worked, no problems since. Sometimes you must take action and have a little talk with your neighbor. I'm not saying go and shoot your neighbors dog because it sounds like a sweetheart but, just have a chat and say you don't appreciate it over on your property, it's yours not his.
PS. If they are free ranging I would suggest penning them up at night, many more predators are out, then you'd have a bigger problem.
best of luck
QP