Besides Upwork, what places do you suggest for freelance work? And the freelance work wasn't on an online marketplace. It was from an ex-boss that gave me side

Besides Upwork, what places do you suggest for freelance work? And the freelance work wasn't on an online marketplace. It was from an ex-boss that gave me side projects that his employees didn't want/have the time to work on. I don't write cover letters unless it's required. Almost all my jobs I apply as a total stranger.. I hardly know any software engineers, and none of my friends on Facebook know of anybody looking to hire one. I only had one friend refer me to a job in 2015. She knew the CEO of a small company. After two onsite interviews I didn't get an offer. It an was odd reason. They changed their mind on giving me a technical assessment because they already concluded that I wasn't fit to do the assessment.