With a 20 hour stop I would say just book a hotel off-airport through discover qatar at the heavily subsidised rates and enjoy yourself. It’s effectively worth just assuming these days that the sleeper rooms will never be available for most (except perhaps at odd times of day)

The staff in AS were all great, recognise you etc and happy to chat, but the lounge is just not set up for the increasing numbers who slip through the sleeper room net.

The buffet snacks area head on as you enter the lounge (keep walking and don’t turn left towards the bar/restaurant) still seems undiscovered though if.you want to eat in peace