It took them a week to respond but this is what they said. It could be a weak Internet signal:
You can also reset your iPad Wi-Fi connection following the next steps:
1. On the Home screen, locate and tap the icon with an image of a gear (“Settings&rdquo.
2. Tap on the option Wi-Fi.
3. Use the option at the top of the screen to turn Wi-Fi off.
4. Then, turn it back on again. This will force your iPad to search for the Wi-Fi network again and rejoin.
I will try next time it happens and hope it works