I just added my domain to my Vercel project and it works properly, but I added a subdomain that points to an external host (a checkout/order page) at orders.mysite.com

The security certificate seems to not want to apply to that subdomain. From what I see the certificate should cover it since it's CN is *.mysite.com

Is this something I have to resolve with the other host or is it an issue with my Vercel settings?