Is there a server not listed for this website? I know ISRG1 and ISRG2 and DigSignatTrust.
I am having an issue with a social chat website that I use Wireclub.com. So I use the Digicert server checker and contacted Digicert to ask them if a server was missing. They responded I needed to contact Let's Encrypt because the website has a certificate from it. Digicert certificate checker tech support sent me the contact link for Let's Encrypt.
So the issue that I'm having is that the Blog feature on Wireclub is not saving Posts. I get error that the form is not secure and autofill has been turned off. Get the same error for Wire Club Help's Start a Conversation and not able to post this request. I attempted to email wire club because they have an email address for support as well as a contact link page but have not received any response after 7 days. I had to EMAIL Wireclub's support because the send button in the support link was getting the same error message as what I was reporting in the Blogs.
I don't see what we can do about it: the website seems to be configured properly with regard to it's certificate (although sending out a very long custom chain, chaining up to DST Root CA X3, but that shouldn't be a problem). And the website redirects to HTTPS.
I can't find the "Wire Club Help's Start a Conversation" to check for the same error you're getting, but I wouldn't be surprised if it wasn't an issue with the website.
Interesting though, I've not seen someone serve this chain combination before, is it a funky way to get android compatibility while still preferring the ISRG Root X2 ECDSA chain?
[Edit: the chain served is up to and including ISRG Root X1, signed by DST Root CA X3 but does not include DST Root CA X3 itself. They are likely using their own custom process to append ISRG Root X2 > ISRG Root X1 to their served chain. ]
It's a hack in the sense that many/most verification processes will stop when they find ISRG Root X2 in their trust stores. Such verification processes, when lacking ISRG Root X2 in their trust stores, will stop when they find ISRG Root X1 in their trust stores. Barring those two conditions, verification processes will fail if they don't find DST Root CA X3 in their trust stores.
(@webprofusion, I know that you are most likely already aware of all this. I provided this information for any who might lack such awareness. )