연고 means 'personal connections' and they could be almost anything you can think of such as your hometown, school, work etc.

연고 means any kind of relationship between people who have something in common. For example, like regionalism, school relations, or kinship. 서로의 공통점을 연결고리로 하여 맺어지는 관계 is a definition of 연고 공동체를 중시하는 한국 사람들은 연고를 중요하게 생각한다. Korean people, who regard community as important, think 연고 is important.