TLS, unknown player error and *.plex.direct

What are you doing with the Custom Server Access URLs?

<?xml version="1.0" encoding="utf-8"?>
<Preferences MachineIdentifier="****" ProcessedMachineIdentifier="*****" TranscoderTempDirectory="/var/tmp/plexmediaserver/" OldestPreviousVersion="legacy" AnonymousMachineIdentifier="*****" MetricsEpoch="1" GracenoteUser="****" AcceptedEULA="1" FriendlyName="Plex****" PublishServerOnPlexOnlineKey="1" PlexOnlineToken="****" PlexOnlineUsername="seblu" PlexOnlineMail="***" CertificateVersion="3" LastAutomaticMappedPort="0" PubSubServer="178.79.165.194" PubSubServerRegion="lhr" PubSubServerPing="26" LanguageInCloud="1" sendCrashReports="0" FSEventLibraryUpdatesEnabled="1" ScheduledLibraryUpdatesEnabled="1" ManualPortMappingMode="1" PlexOnlineHome="1" DlnaEnabled="0" secureConnections="1" CinemaTrailersFromLibrary="0" TranscodeCountLimit="0" logDebug="0" GenerateBIFBehavior="asap" GenerateChapterThumbBehavior="asap" ScannerLowPriority="1" HardwareAcceleratedCodecs="1" LanNetworksBandwidth="10.0.0.0/8,172.16.0.0/12,192.168.0.0/16" WanPerUserStreamCount="****" ButlerEndHour="10" ButlerStartHour="7" CloudSyncNeedsUpdate="0" FSEventLibraryPartialScanEnabled="1" allowMediaDeletion="1" ButlerTaskRefreshLibraries="1" LoudnessAnalysisBehavior="asap" customCertificateDomain="https://plex.domain.tld:32400/" customCertificateKey="****" customCertificatePath="/var/lib/plexmediaserver/certificate.pfx" ScheduledLibraryUpdateInterval="43200" allowedNetworks="" iTunesSharingEnabled="0" customConnections="https://plex.domain.tld:32400/" WanTotalMaxUploadRate="***" TreatWanIpAsLocal="1" TranscoderQuality="0" DlnaReportTimeline="0" TranscoderH264BackgroundPreset="medium" ButlerUpdateChannel="0" LogVerbose="0" BackgroundQueueIdlePaused="0" autoEmptyTrash="0" OnDeckWindow="4" TranscoderThrottleBuffer="60" CertificateUUID="*****" EnableIPv6="0" WebHooksEnabled="1" MinutesAllowedPaused="30" DvrIncrementalEpgLoader="0" CinemaTrailersPrerollID="" CinemaTrailersType="0" GdmEnabled="1" PreferredNetworkInterface="" RelayEnabled="0" HardwareAcceleratedEncoders="1" TranscoderToneMapping="1" DisableTLSv1_0="0" MergedRecentlyAdded="0" ButlerTaskRefreshEpgGuides="1"/>

Notes:

  • customConnections and customCertificateDomain are equal.
  • Server has only 1 IPv4 address (RFC1918)
  • Server has 1 FQDN (e.g plex.domain.tld) which resolve to the local IPv4 address inside local networks and to the ISP public IP otherwise.

Why is HTTPS in that clause as a stand-alone item?

I don’t know, where did you get this output?
Is this related to https inside the customConnections?