Secure Connections not working - running on 1.14.0.5468

I did not expect it to. I just wanted to see if you have a specific error and you did

Nov 25, 2018 17:34:19.344 [4008] DEBUG - CERT: Certificate or intermediate did not exist, fetching a new one.
Nov 25, 2018 17:34:19.344 [4008] DEBUG - HTTP requesting POST https://plex.tv/devices/92a9c0c6362f620c24d3c6baa84278d4f088858a/certificate?version=2&X-Plex-Token=xxxxxxxxxxxxxxxxxxxx
Nov 25, 2018 17:34:20.094 [4008] DEBUG - HTTP 503 response from POST https://plex.tv/devices/92a9c0c6362f620c24d3c6baa84278d4f088858a/certificate?version=2&X-Plex-Token=xxxxxxxxxxxxxxxxxxxx
Nov 25, 2018 17:34:20.094 [4008] ERROR - CERT: Could not fetch certificate from the cloud: 503

You must have purged your cached certificate files and now hit the problem I mentioned with the issuing of new certificates

I have referred this to our operations team who are already looking into it

This just tells me that you are running the Plex Media Server as a Service or Scheduled Task and you are not making use of the existing service wrapper product provided by @cjmurph - see PMS as a service

There are some bits that show in the log that I am not happy with - at some point there were overlapping processes - so service / job started whilst it is already running.

At 17:30 Plex Media Server process was running

Nov 25, 2018 17:30:49.472 [2864] DEBUG - Request: [192.168.2.55:57699 (Subnet)] GET /player/proxy/poll?deviceClass=pc&protocolVersion=1&protocolCapabilities=timeline%2Cplayback%2Cnavigation%2Cmirror%2Cplayqueues&timeout=1 (4 live) GZIP Signed-in Token (Kursah)
Nov 25, 2018 17:30:49.472 [2864] DEBUG - Beginning read from two-way stream.
Nov 25, 2018 17:30:53.900 [2924] ERROR - WinPreferences::getBoolValueWithDefault - GetRegistryValue for logDebug failed: 0x13
Nov 25, 2018 17:30:53.900 [2852] DEBUG - TrayIcon::WindowProc received DisplayIcon timer message
Nov 25, 2018 17:30:53.900 [2852] WARN - Shell_NotifyIcon(NIM_ADD) failed: 0x0
Nov 25, 2018 17:30:53.962 [3268] ERROR - WinPreferences::getStringValueWithDefault - GetRegistryValue for ProcessedMachineIdentifier failed: 0x13

but a new process was started at 17:26 - that must not happen

Nov 25, 2018 17:26:19.906 [3776] INFO - Plex Media Server v1.14.0.5468-5a0183d2c - Microsoft PC x64 - build: windows-i386 english - GMT -07:00
Nov 25, 2018 17:26:19.922 [3776] INFO - Windows version: 6.3 (Build 9600), language en-US
Nov 25, 2018 17:26:19.922 [3776] INFO - 4 3991 MHz processor(s): Architecture=0, Level=6, Revision=15363 Processor Identifier=Intel64 Family 6 Model 60 Stepping 3, GenuineIntel
Nov 25, 2018 17:26:19.922 [3776] DEBUG - "C:\Program Files (x86)\Plex\Plex Media Server\Plex Media Server.exe" 
Nov 25, 2018 17:26:19.938 [2688] DEBUG - Plex for Windows Store application is not installed
Nov 25, 2018 17:26:19.969 [2688] DEBUG - BPQ: [Idle] -> [Starting]
Nov 25, 2018 17:26:19.969 [2688] DEBUG - FeatureManager: Using cached data for features list
Nov 25, 2018 17:26:19.985 [2688] DEBUG - Opening 20 database sessions to library (com.plexapp.plugins.library), SQLite 3.13.0, threadsafe=1
Nov 25, 2018 17:26:20.110 [2688] DEBUG - Running migrations. (EPG 0)

Look into how you start / stop the services. The PMS as Service wrapper I mentioned does make sure all processes are stopped when you select Stop Plex from the service tray app provided

Also make sure you do not have Plex Media Server starting outside the service on login