I don't think it is stress. Sounds like my oldest, Max. I believe he thinks he is being protective and alerting me when he barks. We have tried all of the methods discussed on YT to curb the barking, and I have found traditional training and positive reinforcement to be the most effective.
Keeping Max busy and giving him outlets for his energy are first and foremost. On days when he can get outside a lot, walk long distances, or go on a little adventure with me, he doesn't bark much.
If Max barks in the house at something, I acknowledge him, look out the window or wherever he is barking and tell him everything is fine.
I do my best to redirect his attention from barking. For instance, I'll say "come help me clean the kitchen" or whatever I'm doing at the moment. When all else fails and he is exercising his powerful vocals for fun, I happily ask him, "Shall we take a bath?"
He immediately finds something better to do.
I haven't watched these videos yet (thank you AllDogBoots and Britster), but they address barking issues:
Barking: