Networking event ideas that actually connect people

Why the standard mixer underperforms
Open room, drinks, two hours, good luck. Confident people do fine and everybody else talks to the person they came with. The format is not neutral. It quietly rewards the guests who needed the least help, which is the opposite of what a host is trying to do.
Seat people rather than letting them settle
Assigned tables feel heavy handed for about ninety seconds and then everyone relaxes into them. You are removing a decision that guests find genuinely stressful. If you seat by something other than industry, you also break up the cluster of people who already know each other.
Give the room a job
A question everyone answers, a problem each table works on, a short round where people say what they are looking for. Structure is not the enemy of natural conversation. It is the thing that gets people past the part where they are deciding what to say.
Keep the mixing alive afterward
Every format above works for one evening. What none of them does on its own is survive contact with Monday. A shared directory of who was there lets the connections you engineered keep working long after the tables are stacked.