Hi,
My male dog is peeing and pooing in the house, but only upstairs. I have the staircase blocked but he found his way through. He never ever did this at our previous home. He is a male undesexed, almost 3-year old boxer.
We have moved countries, therefore new house, new neighbourhood, and humid weather..

Could there be something wrong with him, or is he just testing me? I'm the pack leader in the house out of my female desexed boxer, my husband and I.

Do you have any suggestions?

Many things could cause a dog to change its behavior. Have you taken your male unfixed dog to the vet to rule out intestine problems or urinary tract problems etc.

How long hve you been in this home and when did this problem start with him?

Do you have visitors or a new piece of furniture bearing an unfamiliar scent? This could be the reason the dog is doing it to mark territory.

Unaltered dogs will mark, it's a dominance/marking territory thing. Sometimes have them neutered can fix this issue. Make sure you clean the area with a good enzyme cleaner. Vinegar and water will do the trick. Another thing that is important is plenty of out door time and exercise. Brisk walks or jogs create pressure on the bowels creating the urge to "go", making the chances of indoor "accidents" less likely.