A security guard or gatekeeper here implies a person or event that interferes with a business, work, or examination. In other words, this dream implies that what is planned and what is being pursued will not go smoothly and will be delayed. However, it only implies that it will be difficult to see good results right away because it is not the right time, not to say it is impossible. So you’d better take your time and wait for the next chance instead of being impatient.