Plex client cannot sign in

Server Version#:
Player Version#:6.18.0.4847
<If providing server logs please do NOT turn on verbose logging, only debug logging should be enabled>
Hello !
I have old Amlogic s805 K1 android box with Version: 4.4.2
the latest Plex client supporting KitKat cannot sign in to my plex server.
here is log:
logs

This android version is not supported by Plex. It hasn’t been supported for years, actually.
Most common issue with old OS versions are missing root certificates, which are necessary for connecting to plex.tv.

Thanks Otto,
will find a way to update the certificates and will try again.