Check and clear the pump and skimmer basket of any leaves.
Check the pressure and back wash your sand filter or hose out your cartridge filter or even soak in filter cleaner in extreme cases.
The cleaner may be blocked with leaves or rocks etc. also check the hose for cracks and its been fitted correctly to the vac plate.
Other solutions include adjusting the autocleaner speed and returns/ eyeballs or your autocleaner may need replacement parts.
Or your pool may need to be fitted with a Pool Leaf skimmer, this collects the leaves before the sink to the floor.