Why couldn't NordVPN validate the TLS certificate?

NordVPN couldn't validate the TLS certificate likely due to an issue with the certificate chain, the server configuration, or local issues on the user's device. The problem might stem from an expired certificate, a network error preventing proper verification, or incorrect system time settings on the local machine. In some cases, server-side misconfigurations such as incorrect certificate installation or intermediate certificates not being properly served could be the culprits. Additionally, trust issues with the certificate authority (CA) that issued the TLS certificate could also prevent validation if the CA is not recognized or has been compromised. It's important for users to ensure their device's time and date are accurate and for service providers like NordVPN to maintain proper server configurations and update their certificates regularly to avoid such issues.