
This is the age where male to male aggression tends to start. A young male has a lot of testosterone which has a negative effect on how other males perceive him, so often a previously male freindly dog will be getting bad vibes and act defensively. Also of course the increased testosterone may be making him want to take on the whole male world.
You will have to guide him through this stage, avoiding confrontation and preferably keeping up the socialisation but not ridking any harm to him or any other male dog. Insist on him being quiet and clam artound other makle dogs, but keeping a safe distance (on the lead). this is what people will be doing all the time at shows you will ahve noticed.
If he is going to calm down and bew hapy with males again this will happen when he reaches full maturity and the testosterone levels reduce. On the pother hand like with a lot of breeds where males are intolerant of each other you will just have to manage him so that he never has the opportunity to get in a fight. This means more obedience training and vigilance. Avoid any eye balling withother dogs etc.