Some dogs will genetically be more anxious/aggressive than others. I have a rescue pup that tends to scare visitors too (people she doesn't know), so we hired a trainer, and it actually helped a lot, but I still keep her crated when young kids come to visit. Like yours, it started around 5 months.
I highly doubt that neutering will change the behavior at all, so don't expect miracles there. Get a trainer. If you can't control it, crate him when people come over.
I highly doubt that neutering will change the behavior at all, so don't expect miracles there. Get a trainer. If you can't control it, crate him when people come over.
