I feel like the key to making friends (that no one ever talks about) is having common shared stakes. You can go to a meet up but you will never make friends there because there is no requirement that people come and once there you don't have to work with people to do things. I find that I can make solid friends with anyone if we have to do things together. Though I admit sometimes that doesn't even work.

For me I find the best and kind of only way to make new friends is to do something... volunteer on a group that is tasked with a specific "making something happen" where people have to show up. For me I am on my condo board of trustees. Volunteer at a place you kind of have to go, say like taking care at pet shelters.