Unable to claim server

Plex Media Server
1

:wrench: Hardware / Environment

  • Device: Western Digital MyCloud PR4100

  • CPU: Intel Pentium N3710

  • OS: WD OS5

  • Plex Server versions tested: multiple, latest attempted 1.42.x

  • Client device: macOS laptop

  • Access over LAN only

  • Local network:

    • NAS IP: 18.8.0.2

    • Subnet: 18.8.0.0/24
      :warning: This is not a standard private LAN subnet (not 10.x / 172.16.x / 192.168.x), which appears important.

:red_exclamation_mark:Current Problem

Whenever I try to open Plex Web:

:right_arrow: Not Authorized – You do not have access to this server

This happens:

  • even when Plex is freshly installed

  • even during the initial setup wizard

  • even when HTTPS works

  • even after successful claim

  • even after forcing allowed networks/security changes

So I cannot complete setup, sign in, or use Plex at all.

:white_check_mark: Things Confirmed Working

  • Plex Media Server starts

  • Port 32400 is listening

  • HTTPS access works

  • Plex Web loads (but refuses access)

  • Logs show Plex sees my requests as LAN/subnet

  • Claims succeed

  • But access requests get logically rejected (401 / 406 in logs)

:test_tube: Troubleshooting Already Performed

:one: Initial troubleshooting

  • Restarted Plex multiple times

  • Stopped Plex via SSH (pkill)

  • Checked networking (netstat)

  • Checked Plex logs

  • Multiple claim attempts:

    • normal UI

    • enforced via URL

    • using plex-claim-server.sh

  • Claims reported success:

    Plex Media Server successfully claimed

Still → Not Authorized

:two: Advanced authorization & network configuration

Manually edited:

/mnt/HD/HD_a2/Nas_Prog/plex_conf/Plex Media Server/Preferences.xml

Added/verified:

allowedNetworks="18.8.0.0/24"
DisableRemoteSecurity="1"
RequireLocalAuth="0"
secureConnections="0"

Even with these present, behavior did not change.

Sometimes Plex refused HTTP and forced HTTPS,
but even with HTTPS access → still “Not Authorized”.

:three: Clean full reset and reinstall

Performed a complete uninstall & wipe:

:check_mark: Stopped Plex
:check_mark: Uninstalled via WD App UI
:check_mark: Deleted:

rm -rf /mnt/HD/HD_a2/Nas_Prog/plex_conf
rm -rf /mnt/HD/HD_a2/Nas_Prog/plexmediaserver

:check_mark: Rebooted NAS
:check_mark: Installed fresh Plex from WD App Store

:police_car_light: Result After Fresh Install

On first startup:

Redirects to:

http://18.8.0.2:32400/web/index.html#!/setup/xxxxxxxx

Instead of setup page, I get Not Authorized again.

So I cannot:

  • complete setup

  • link account

  • create libraries

  • use Plex at all

2

This is not a private IP range. You will have a hard time claiming a server that is on a public (routable) network.

3

Hello this is my internal home ip adress. I am using it voluntarily instead of 192.168.0.0

4

This is a very bad decision. There are plenty of alternate adress spaces available which are “private”: Private network - Wikipedia
A very easy one is to change it to 10.8.0.0/24 instead.
If you are using a CIDR netmask of “/24” you could even have used 192.168.x.0 where x was replaced by any number from 1 – 255.
That is 255 possible alternatives to 192.168.0.0/24 without the necessity to use a public IP space – which was bound to get you into trouble sooner or later. Like now.

5

and

6

18.8.x.x collides with the public IP space of the Massachusetts Institute of Technology.

This is why you must change it to be in the known-safe address ranges for your home.

The choices are:

  • 192.168.x.x
  • 10.x.x.x
  • 172.16.x.x → 172.31.x.x

This is per IETF standard.

More info is here.


NetRange:       18.0.0.0 - 18.31.255.255
CIDR:           18.0.0.0/11
NetName:        MIT
NetHandle:      NET-18-0-0-0-1
Parent:         NET18 (NET-18-0-0-0-0)
NetType:        Direct Allocation
OriginAS:       
Organization:   Massachusetts Institute of Technology (MIT-2)
RegDate:        1994-01-01
Updated:        2025-12-02
Ref:            https://rdap.arin.net/registry/ip/18.0.0.0
7

many thanks I fixed it