I'm a 30 year old male and I've always found it easy to make male friends and maintain meaningful male friendships. That includes men of all ages. I don't know how, except perhaps by being genuinely interested in their lives and projects they're working on. I'm guilty of being too honest for my own good which may or may not play a role.

Despite treating females exactly the same, more often than not they mistakenly assume I'm romantically interested in them. When I was a teenager I was often taken aback by their negative reactions to my messages. I'd copy-paste the offending my message to a male, or have the same conversation with a male, and the men always reacted positively. It was quite puzzling.