I was in WDW the first week of May. I installed the My Disney Experience app a few weeks before departing and had no issues using it to view my FastPass and reservations. When we arrived in Florida, I still had no trouble.
But when we got on the trolley to go from the parking lot to Animal Kingdom, the app couldn't connect. I tried using Disney wifi and I tried turning off wifi. No dice. Hours later, it started to work. I had the same experience 2 days later at Magic Kingdom.
I don't know if my experience was just a fluke, but my advice is to screen shot your FastPass selections so that if the app isn't working, you can still see what time you need to be places.
But when we got on the trolley to go from the parking lot to Animal Kingdom, the app couldn't connect. I tried using Disney wifi and I tried turning off wifi. No dice. Hours later, it started to work. I had the same experience 2 days later at Magic Kingdom.
I don't know if my experience was just a fluke, but my advice is to screen shot your FastPass selections so that if the app isn't working, you can still see what time you need to be places.