Some schools have a proxy in place to use for school web filtering. These only work while on-site at a school. Therefore you will need to disable the proxy when at home and enable them when in school.
Please see the below guide on how to enable the proxy whilst at school.
1. Go to the Start Menu
2. Open Settings
3. In the search box type proxy
4. Click "Change Proxy Settings"
5. Turn "Use a Proxy Server" On