Could be some incompatibility or a weak signal. On many campgrounds my iphone would not connect but the ipad and laptop have stronger wifi antennas.
Now if only campgrounds could get into this century and realize that us young people live on the Internet. We are the people who are going to make or break the campground industry once all the baby boomers retire from camping.
I use my phone as a wifi hotspot. 2.5GB plan for 60$ and I can add extra 1GB for 10$ each. This is what I do on most campgrounds since wifi is usually not working or too slow to be of any use.