I'm facing the same issue for my this website, https://www.onlinevidyalaya.net/. Older Android devices and Windows 7 users are not able to access the website.
To solve this issue, I followed this guideline,
- Imported isrg-root-x1-cross-signed.der into trusted store
- moved isrgrootx1.der (self signed certificate) to untrusted store
- Reissued let's encrypt certificate again (I'm using plesk panel)
- rebooted the server (using windows server 2012 r2) 3-4 times.
- manually tried to bind certificate from IIS manager also.
Still facing the issue. Can anybody please help me on this issue?
SSL Server Test: opensea.io (Powered by Qualys SSL Labs) (this is not my website, they have resolved the issue)
SSL Server Test: opensea.io (Powered by Qualys SSL Labs)
showing 3 certificates under the additional certificates section.
SSL Server Test: onlinevidyalaya.net (Powered by Qualys SSL Labs) showing only 2 certificates under the additional certificates section.
Have a good day!