Plex Server and 401 error with nginx Proxy Manager

[PlexNanotekDynamic]

Plex Web: 4.141.0
Plex-Server 1.41.3.9314

I need some help with my Plex-Server behind nginx Proxy Manager.
Short: I get a 401 error with using the external domain <plex.example.com> (real domain registered at cloudflare DNS)

Long:

Let’s Encrypt certificate with Cloudflare-DDNS:

apt update && apt install -y certbot python3-certbot-dns-cloudflare

mkdir -p /etc/cloudflare
chmod 700 /etc/cloudflare
touch /etc/cloudflare/credentials.ini
chmod 600 /etc/cloudflare/credentials.ini
nano /etc/cloudflare/credentials.ini
=====
dns_cloudflare_api_token = 0123456789abcdef
=====

certbot certonly --non-interactive --agree-tos --register-unsafely-without-email --dns-cloudflare --dns-cloudflare-credentials /etc/cloudflare/credentials.ini -d <plex.example.com> --dns-cloudflare-propagation-seconds 60 

crontab -e
=====
0 1 * * * /usr/bin/certbot renew & > /dev/nul
=====

touch /etc/letsencrypt/renewal-hooks/post/create_p12.sh
chmod 755 /etc/letsencrypt/renewal-hooks/post/create_p12.sh
nano /etc/letsencrypt/renewal-hooks/post/create_p12.sh

=====
#!/bin/sh

openssl pkcs12 -export \
  -out /var/lib/plexmediaserver/plex_certificate.p12 \
  -in /etc/letsencrypt/live/<plex.example.com>/cert.pem \
  -inkey /etc/letsencrypt/live/<plex.example.com>/privkey.pem \
  -certfile /etc/letsencrypt/live/<plex.example.com>/chain.pem \
  -passout pass:abc123 \
  -certpbe AES-256-CBC -keypbe AES-256-CBC -macalg SHA256

chmod 755 /var/lib/plexmediaserver/plex_certificate.p12
=====

sudo chmod u+x /etc/letsencrypt/renewal-hooks/post/create_p12.sh

certbot renew --force-renewal

set up plex

• Secure connections: Required
• Custom certificate location: /var/lib/plexmediaserver/plex_certificate.p12
• Custom certificate encryption key: abc123
• Custom certificate domain: <plex.example. com>
• Enable Strict TLS configuration
• Custom server access URLs: https://<plex.example. com>:32400, https://<plex.example. com>:443
• IP-addresses that don’t need an authentication: <plex.example. com>
• Disabled remote access

nginx Proxy Manager

• Domain Name: <plex.example. com>
• Forward Scheme: https - 192.168.1.42 - 32400
• Block common exploits: true
• websocket support: true
• Force SSL: true
• HTTP/2 support: true
• HSTS enabled: true

It was working 1 time, and now I get a 401 error that says, that the domain need a user and password.

What I tried so far

• adding local IP of the server to “custom server access” and “IP that dont need an authentication”
• changed https to http in nginx
• tried ports 80, 443, 43200 in nginx
• disabled HTTP/2 and HSTS in nginx
• disabled websockt support and block commain exploints in nginx
• enabled remote access and tried port 32400 and 443

[PlexNanotekDynamic]

no one?

[elephantgrenades]

Edit: added clarity, my experience might not be exactly the same issue as described above.

I experienced a 401 Unauthenticated error after setting up nginx a few days ago. It worked the first time and automatically redirected to the sign-in page, but subsequent attempts didn’t work. I noticed that after going through my history, the plex web URL became https://plex.mydomain.com/web/index.html#!. I updated my nginx config to include a custom location (IP and port should be the same as your local host and plex port, typically 32400):

then, I added the rewrite to my location to make sure it redirects to /web/:

After I saved, I tested across multiple devices, cleared browsing cache and tried again, no more 401.

This stackoverflow discussion led me: Getting a nginx reverse proxy to work with plex - Stack Overflow

[PlexNanotekDynamic]

Thanks a lot. I will save this for later. I switched from NPM to NPM+ (GitHub - ZoeyVid/NPMplus: improved fork of nginx-proxy-manager) and its working without any additional config.
NPM is outdated and not so well maintained. NPM+ is a fork with a lot of work behind.

[bxlouis]

I am experiencing the same issue with Traefik but even adding the /web at the end of my Service’s URL does not work. Any idea what might be wrong?

  services:
    plex-svc:
      loadBalancer:
        passHostHeader: true
        servers:
          - url: "http://10.0.1.170:32400/web"

I rolled back to PMS v 1.41.6.9685 for now as it fixes the issue.