My website is being blocked only by devices on BT WiFi

[airslip]

Hi BT Community,

I am the founder of Airslip and we are having website problems with BT WiFi only. The website can be viewed at https://airslip.com however, devices connected to BT WiFi throws an error. The exact error on chrome is "Site can't provide a secure connection. airslip.com uses an unsupported protocol. ERR_SSL_VERSION_OR_CIPHER_MISMATCH"

The domain is fairly new, it was purchased in February 2020 but it seems like BT doesn't trust it. 

This is very frustrating as we are crowdfunding soon and cannot let this problem get in the way of funding. Any help would be great.

[-Richie-]

Loads fine for me using BT broadband, I don't have Chrome installed though, I tried with Firefox and M$ Edge.

Have you tried other browsers ? I might be a Chrome issue and not ISP related.

[licquorice]

Works for me with Firefox and Chrome.

[airslip]

I have attached the three photos on mobile and computer. screenshot is using firefox. 

[imjolly]

@airslip 

Are the people who are having problems using BTWIFI or are they using their home BT broadband?   BTWIFI is the newt work available to BT customer when out and about and is unsecured 

[gg30340]

It is BTWeb Protect that is blocking the site because it is not secure. Are the sites certificates etc all up to date.

[-Richie-]

[airslip]

@imjolly Thank you for getting back to me. They are using only BT broadband. It seems to be a very small number of people only on BT who are experiencing this issue.

[airslip]

@gg30340  The website is secure. I have paid for a GlobalSign certificate for SSL, enforced HTTPS redirect and enabled HSTS.

[imjolly]

@airslip 

it may well be that @gg30340  suggestion is the problem as BT are activating web protect automatically and customers can then if they want turn web protect off