i tried every think i read on the web but doesn't work for me. The solution is extremely easy for me. I change the radio channel to a less crowded on my router, so it speeds up and doesn'r lose-conflict connection download. But this works for me, 911 is more general issue. Most people solved this by wiping play store and playstore service cache, or uninstall and reinstall google play store update.
By the way first of all try to download using other wifi.