works fine on PN on VPN ON or OFF and using 1.1.1.1 DNS servers,
you may have a DNS issue, or a blocklist issue, as due to IPv4 has long run out now, we have tens of millions of websites sharing IPv4 IP addresses with other websites (only sorted out through their website name on the IP), it could be YOUR website is on a server that has a NASTY/NAUGHTY website on it - thus the IP is Blocked by some companies...
as it works off Plusnet, Nord and Cloudflare DNS I don't think it is that - so it is most likely a filter issue as above - get on a website hosting FORUM (https://www.webhostingtalk.com/) and ask on there too, what the possibilities could be?
