If you get a weird message that says something about a network refusing to connect, you've likely got some firewall issues at your school. To see if it's the hardware, the network, or the website, here are some things to try. Let's assume you're running into problems on your school's hardware on your school network.
First, whip our cell phone at school. Turn OFF the wifi so that you're using cellular data (it'll just be a bit), and open up the website. If you're able to access everything here, then you can sure it's either the network or some restriction's on your school-issued computer.
Try logging into the website on your home wifi. If it's fine there on the same device it was a problem at school, then your school wifi is the issue. Let your IT department know that.
If the school-issued device still has problems on your home wifi, then try a different device (like your cell phone) at school.
Let your IT department know what you find, and feel free to copy us on the email. Let them know that our team would be happy to help them troubleshoot to make sure you've got access to the best lessons around.