Sometimes one or two of them work sometimes none work sometimes all work, But none of them is stable,, It gives me " Your connection is not private" "NET::ERR_CERT_INVALID" and the attached photo is the certificate
I have tried all but the admin domain repeatedly. But, I am not using a browser but I am using openssl. For example:
echo | openssl s_client -connect deliverymasrapp.com:443 -servername deliverymasrapp.com | head
If you get a different result from openssl and a browser I would start to suspect the browser. For example, does it have a security plug-in that inspects https traffic? Sometimes antivirus programs intercept traffic and replace with their own certificate so they can fully assess the traffic. I do not know why it would not be consistent I am just noting.
Are there a wide variety of machines having a problem? Do you see the problem using other browsers or just the same one always?
Rudy, I think when they said "mobile data" they meant cell too. But fair to double check.
@AR97 What results do you get from repeating openssl command?
Also, I see from google that other people have seen that exact testexp certificate even with all the other info on it (expiry date and so on). So a good guess is some vendor product or one that has recently been updated.
I see your certificates just fine. Your nginx config looked fine (what you showed). Here is a website that will check your certs. Run it several times and see what you get (always fine for me) - it uses openssl to check: https://decoder.link/sslchecker/deliverymasrapp.com/443