Poodle dog gets more aggressive after he has been neutered!!!

Has anyone had a problem with their dogs being more aggressive after they have been neutered?
Zak was neutered at 5 years of age. That’s been about a year and a half ago. I thought they were supposed to be calmer but that’s not what happened with him. While walking the together this weekend another stray dog came up and started circling us. Zak went crazy. Growling uncontrollably. Later that afternoon a neighbor and her two boxer dogs came to visit. All went well with no fights. I was just wondering if anyone else has had this aggression problem after their dogs have been neutered. #standardpoodle #aggressivedog