DualSense Pairs With My PC Then Drops Off A Few Seconds Later, Every Time

First, the practical bit since you have a deadline: wired works and wired is tournament-legal nearly everywhere, so you have a guaranteed fallback. Now the actual fix, because this one is usually solvable in ten minutes.

A connection that establishes and then dies on a short, repeatable timer is characteristic. A genuine range or interference problem is erratic, dropping after different intervals and often recovering on its own. A consistent five to ten seconds points at one of two things. The first is a stale pairing record: the controller and the adapter each keep a link key, and if they disagree the connection authenticates, fails a check, and tears down a few seconds later. Re-pairing without removing the device first does not clear this, which is why fifteen attempts changed nothing. You have to remove the device from Windows, reset the controller so it discards its side, and pair fresh.

The second is Windows power management. Bluetooth adapters, especially on laptops, have a setting that lets Windows turn the radio off to save power, and with an always-streaming device like a gamepad it can cut a connection almost immediately after it forms. It is a single checkbox in Device Manager and it is worth clearing on any laptop you game on.

Work through the steps in order. Do the reset and the clean re-pair as one operation rather than skipping between them, because doing half of it leaves the mismatched key in place.