How do I stop captive.apple.com from blocking my internet access?

This may help you --> Use captive Wi-Fi networks on your iPhone or iPad - Apple Support

You will need to provide information on your WiFi setup if you are trying to connect to your personal network.

• Brand/model of router
• Mesh Network?
• Using Extender?
• Are you being asked for a Password?
• Are you connecting to the correct network set up on your router? Xfinity for example provides WiFi that is a shared network from other subscribers and will appear on your WiFi page as "xfinitywifi". This network is actually a captive portal where you will need to provide your Xfinity login and password for access. This is not the wifi network you want to use when setting up your Xfinity router and you will need to select the private wifi network that it is broadcasting.