Hey @rhbirkelund. After reading through the thread, and a lot of failed attempts, I'm hoping that you can help.   I've managed to create the certificate files (0000_cert.pem, 0000_chain.pem, and 0001_chain.pem) using Certbot and the CSR file I generated on the MX page, but even if I replace the invalid root certificate in 0001_chain.pem with the ISRG Root X1 certificate, I still get the following error "Unknown Error Failed verifying Device Cert with Cert Chain" when I upload the files.   Here's exactly what I do:   - When generating the CSR file on the MX page, I input into the Common Name field the domain name of the A record that points to the IP of my MX, and I leave the rest of the fields blank - I then use the CSR file to generate the certificate files using Certbot - I replace the invalid root certificate inside 0001_chain.pem with the ISRG Root X1 certificate - I upload the 0001_cert.pem as the Device Certificate, and the 0001_chain.pem as the CA certificate   Any insights into what I could be doing wrong? ... View more