The access queue is the thing that confuses first time visitors, because it looks like a failure and it is not. Here is what it is, why it exists, and the one behavior that makes it work for you instead of against you.
What it is
When many users hit a mirror at the same time, the market shows a loader page with a message telling you to wait and not to refresh. That page is the queue. It is a line, not an error. The market admits visitors in batches rather than all at once, which keeps the server from collapsing under a sudden crowd and makes it expensive for a scraper to pull the whole catalog in one pass. You are in the line. The page is telling you to stay in it.
Why refreshing makes it worse
The queue assigns you a position when you first arrive. Every time you refresh, the server sees a new request and puts you at the back of the line again, because it cannot tell that you are the same person who was already waiting. So the instinct to refresh, the one that fixes a slow page anywhere else on the internet, does the opposite here. It resets your place. The correct response is the less satisfying one. Leave the tab open, do nothing, and wait. If you need to do something else, switch to another tab and come back. Do not touch the queue tab until it clears on its own.
How long it takes
Under normal peak conditions most queues clear within ten minutes. During a rotation, when a large share of users move to a new address at the same time, the queue is longer and can take fifteen to twenty minutes. If a queue drags well past that, the market may be under heavier load than usual, and the sensible move is to switch to the next mirror rather than keep waiting on a congested one. Switching is not giving up. It is using the redundancy the mirror system exists to provide. The queue is a small price for a market that stays up under pressure, and the buyers who learn to sit still through it are the ones who stop treating it as a problem.