I just found a "trick" that seems to dramatically reduces my WiFi sleep issues. Time will tell but so far so good.
If you go to your WiFi network that you use and click the "I" button, there is a setting at the bottom called "HTTP PROXY" - it defaults to off, but if you change it to Auto, then the WiFi doesn't sleep when the iPad sleeps.
I found this trick on YouTube and it seems to work. Now, my iPads instantly connect when waken from sleep.
Hope this lasts because this has been a major pain. I have several iPorts around the house and it really is frustrating to have to wait minutes when I get to an iPad to do anything in the house. It was so bad that I ended up using my Russoud App to control zones on my phone because it doesn't have a delay.