Android TV no longer connects

[TheDreadPirate]

Depending on which CA your cert is signed by it is quite possible the TV doesn't trust the certificate.

https://letsencrypt.org/certificates/#root-cas

The X2 root CA was stood up in 2020. Depending on when your TV last received an update, it probably doesn't trust that CA.

Without a firmware update I'm not sure there is much you can do besides what you already did. AFAIK, there is no easy way to side load certificates to the trust store.

One thing you can explore is changing things around in caddy to provide your clients a cross signed certificate chain. Cross signed means that X1 will sign off on certs generated by X2. The link above includes links to download the cross signed certs for the root and intermediate CAs. LE's X1 root authority should still be trusted by TV and a cross signed certificate chain may allow your TV to trust your certificate.