Omada is a community and small group of people working on hosting free and open source services on the basis of freedom, privacy and decentralization. One of these services are Omada DNS, which breaks lightspeed, securly, goguardian and more from working simply using a network setting. If your school has "Managed networks" on, this will not work.
Go to settings -> Wi-Fi -> Known Networks
Select a network
Dropdown the "Network" option
Click "Name servers -> Custom name servers
Set the first field to 167.86.91.171, the rest can be 0.0.0.0
Repeat steps 3-5 on all other networks
Restart your chromebook to clear cached blocked websites.
If you have an managed network use an mobile hotspot then edit it.
Or use Caub+DNS+Proxy Editor
Alot of ONC's here https://github.com/StarRepo444/ONCfiles