BT Broadband Users Can't View My Website

[andycrisp]

I run a small business with a website www.masonbullock.co.uk.

When someone on BT Broadband tries to access our website, they get a warning as follows: Sucuri Website Firewall - Not Configured. It is the same message as on this page (https://docs.sucuri.net/website-firewall/troubleshooting/domain-not-configured/)

Our domain no longer points to Sucuri's firewall. After clearing the cache, the problem still occurs.

This only happens on BT Broadband. The fact that the issue only occurs on BT Broadband indicates pretty strongly that it's caching related. Our web host support says: The issue with the Sucuri Firewall is that it only appears when I connect to my home BT broadband. If I use 4G or any VPN's I do not see this error. I am still getting it now so I am not sure as to why this has not cleared off the BT network. 

They have not been able to resolve it. Their final comments were: Sadly I don't think we have the control of what is happening as I believe it's coming from BT if they are blocking your website. I'm sorry but it may need to be a matter for them to resolve.

Can someone resolve this please?

[CJT80]

@andycrisp 

I am a BT customer and can access the site without any issues.

[licquorice]

Nothing to do with BT, your site is fine with IPv4 but not with IPv6.

[herbie1]

No problem here on BT.

[andycrisp]

Thank you for your response.

Our web hosts say:

Your site doesn't have an ipv6 address so that can't be the issue. 

If you want to test some more things that I can't from my end.
On the offending network open a command line terminal, proceed to enter "nslookup masonbullock.co.uk" screenshot the output and send it to me. 
Can you also enter "tracert masonbullock.co.uk" and send me the output?
Also what do you get if attempt to go to https://cpanel11.hostinguk.net:2087/

Is this anything you or anyone else on this forum can help with please? I can't do it myself because I'm not on BT.

[licquorice]

Well according to the screenshot, you do have an IPv6 address and that is what is failing from the tracert

[andy_3_913]

Might not be much help, but I'm with BT and just thought I'd have a look

[licquorice]

@andy_3_913  I suspect if you try it with IPv6 disabled you will be successful

[Marcel · Accepted solution]

If you look up the DNS for the IPV6 address, it's still pointing at Sucuri but the IPV4 address is pointing at the hosting service provider.

[andycrisp]

Thanks to everyone who contributed to this thread. As a result, a serious problem has now been solved and we're already seeing an increase in website visits as a result. I appreciate the time and effort you have taken to help me, especially as you did so without any reward for yourselves.