Why is a Firewall blocking a website on my ipad

If accessing the Internet thtough a MODEM/router source, the MODEM/router maybe setup with Firewall security settings and levels that prevent some Websites from loading if such Websites have a possibility of loading/introducing some malicious code or data.

You would need to modify the MODEM/router settings to reduce the security settings of the MODEM/router Firewall.

You would need to consult the MODEM/router instructions needed to access the MODEM/router software to be able to alter those Firewall settings.

Good Luck!