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 at the top right (You will need to enter their iPad 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.

You may need to re-enter the subnet mask address before Save becomes available.

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