Below is how to Set a Static IP on an iPad to attempt to fix them not being able to connect at home.

Open iPad Settings
Go to Wi-Fi
Click edit on the Top Right (You will need to enter their Password)

Select their Home Network and Click the ( I )

Click "Configure IP"
Select "Manual"
Change the Settings to the same as below and click save.

Go to "Configure DNS"
Click Manual and set the Servers as 8.8.8.8 and 9.9.9.9
Click Save.