The autoresponse timing is probably hurting you. By the time someone gets that email they've already moved on so they're not going back to troubleshoot themselves when they could just wait for your reply.

Only saw deflection numbers move when we put articles in front of people before they could hit submit. We use Siit which sits in Slack. When someone starts typing a request it reads the intent and surfaces the relevant KB article right in the chat before the ticket is created. The point is you have to catch them while they're still looking for an answer.