I am using QUIC.cloud for connecting LSCache to them for DNS, SSL and CDN. The certificate chain they installed causes browser requests from Edge or Chrome browsers on Android less than 7.1 to cause a "not trusted" error. I understand that LetsEncrypt has a solution for this and was wondering how I could get the proper chain from you so I could install it manually through QUIC.cloud (they make provision for third party certificates). I realize QUIC.cloud uses LetsEncrypt, but for some reason their deployment doesn't work so I thought if you could supply me with a working certificate, I could install it manually through their manual entry process. They can manually install the certificate and private key.
Are all the certificates stored in the same place? I can see server.crt and server.key. There are two certificates in server.crt and one in server.key. In other words, would the hosting provider store a certificate in one place and the CDN store one in another place. If so, I can install certbot and have it install the long chain certificates.
It depends on how much control you have over the system.
If none, ask the provider for assistance.
If root, then you can control the ACME client and switch chains OR even to another ACME CA.
If somewhere in between, it really depends on the access you have to the location of the cert files, the amount of scripting that can be done and your willingness to roll your sleeves up and create your own solution.
You might be able to put the site behind Cloudflare CDN and be done with it.
[note: I'm not 100% certain Cloudflare supports QUIC - but it's 2022 and they should]