Hi Astr0Wrld,
Thanks for reaching out using Apple Support Communities. Here to help.
We understand you are having trouble getting certain websites or apps to load over cellular data, is that right? We have a few ideas of things to check.
Do you have any VPN applications installed to your device or to your network? Virtual Private Networks take steps to route or hide your network traffic, but in some situations can result in difficulties accessing the network if not configured a specific way. If you do have any VPN applications installed, try disabling or deleting them and see if this resolves your ability to access while on cellular data. You can test this behavior from anywhere by temporarily disabling Wi-Fi.
It also is possible to disable certain services from accessing cellular data. These settings can be found in the iPhone Settings > Cellular. Scroll towards the bottom and you will see all apps and services listed. Ensure that Safari, YouTube, or any other apps you are having trouble with are not disabled here. You can read more about this functionality in the link below.
Check the cellular data usage on your iPhone and iPad
Hope this helps! If we can help any further please let us know. Take care for now.