Phones no longer support Let Encrypt

[Alcormizar]

Can confirm, all Yealink phones we have installed that connect via TLS to Let's Encrypt certificates stopped working. We had to go through all of them and put " Only Accept Trusted Certificates" to Disabled to be able to make them connect again. The root certificate for let's encrypt in all Yealink phones has expired (even with latest firmwares) and causing disconnects.

Tried to upload the new root certificate, got "certificate is prefabricated"

Tried to upload intermediate certificates, they get uploaded but don't solve the problem since the expired root certificate is taking precedence.

This is very poor for a company like Yealink who should make sure they stay up to date with root certificates to avoid situations like this . Please provide firmware updates even for old phones so we can safely use TLS security again.

Thanks!