[amerkhalid]

I think you can still reconnect with your former colleagues even if you haven't talked to them in a while. Starting a business or looking for a new job is a great excuse to do so. I have been on both sides of conversations and it never really bothered if someone messaged me out of blue or didn't respond to my message.

And if you do message, keep it short and to the point, only time I get really annoyed is when someone starts a conversation, asking about work and family then after several messages, they would bring up their real motivation. Usually, it is MLM related and when I say hard NO, they disappear again.

Something like "hey X, been a while, hope you are doing well. I am freelancing these days and looking for a new project. My main focus is tech a but can also do tech b and c. Please let me know if you have any leads. I would truly appreciate it."

And if you really want to build better relationship, you could say something like, "And we should grab coffee one day and catch up. I miss working with you."