The LetsEncrypt Root Certificate (DST Root CA X3) will expire on 30-Sep-2021. While there is a new Root Certificate available for a while, some devices and browsers might show an error after that date as they might not have got the new Root Certificate. Here is the simplified overview: Old LetsEncrypt chain: DST Root CA X3 : Expires 30-Sep-2021 R3 (Intermediate): Expires 29-Sep-2021 New LetsEncrypt chain: ISRG Root X1 : Expires 04-Jun 2035 R3 (Intermediate): Expires 15-Sep 2025 If Read more [...]