LG TV in same network can access Plex but outside cannot

[OttoKerner]

Pretty likely that you cannot fix it, unless you add hardware which replaces the not-so-smart player in these TVs.

Important information about Plex for smart TVs after September 30, 2021

UPDATE: It appears that all Tizen-based Samsung sets are likely affected by the cert change and will thus need the app and server configured to allow insecure connections. On September 30, 2021, some older smart TVs (some Samsung, LG, Vizio, Hisense, and other unsupported TV platforms) will no longer be able to use secure connections to communicate with Plex Media Servers. These devices are no longer supported by their manufacturers, and won’t be receiving an update needed to continue making se…