Manually made SSL (letsencrypt) on Portainer + OMV

Nextcloud version (eg, 20.0.5): 25.0.2
Operating system and version (eg, Ubuntu 20.04): Linux pi 5.15.74-v7l+ #1595 SMP Wed Oct 26 11:05:08 BST 2022 armv7l (Raspbian Lite, head when I boot Raspbian)
Apache or nginx version (eg, Apache 2.4.25): nginx 1.18.0
PHP version (eg, 7.4): php 7.4.30

The issue you are facing:
When I access the nextcloud website, I see SSL error:
“NET::ERR_CERT_AUTHORITY_INVALID”

I issued letsencrypt certificate with my computer certbot (manual, DNS verification) and properly configured to OMV workbench, Portainer Web, File Browser.
But, even though I have a verified certificate, I can’t configure it to my Nextcloud. It doesn’t provide any ways online.

I’ve googled it and tried various ways such as make certificate file on nextcloud directory and nextcloud.enable-https (command not found error was established).

Any ways to configure letsencrypt certificate?
I have access to ssh of original Raspberry Pi directory and shell via Portainer.

Also, installing nextcloud with snap didn’t work for me and I can’t try this since server is in production.

More Info.
I tied 183.xxx.xxx.xxx addr. (Raspberry Pi Addr.) to xxxx.xxxxx.xyz (domain) via Cloudflare (proxy is not applied)

Is this the first time you’ve seen this error? (Y/N): N (from yesterday night ~)

Steps to replicate it:

  1. Visit IP address or domain
  2. See NET::ERR_CERT_AUTHORITY_INVALID error

The output of your Nextcloud log in Admin > Logging:
Too large to post: retrieved from [root domain address]/settings/admin/logging
https://scianio.notion.site/Nextcloud-log-c13d332db263406db2bb078751347109

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php
$CONFIG = array (
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'datadirectory' => '/data',
  'instanceid' => 'ocy7c05g5e4r',
  'passwordsalt' => '*********',
  'secret' => '***************',
  'trusted_domains' =>
  array (
    0 => 'xxxx.xxxxx.xyz',
  ),
  'dbtype' => 'mysql',
  'version' => '25.0.2.3',
  'overwrite.cli.url' => 'https://xxxx.xxxxx.xyz',
  'dbname' => 'nextcloud',
  'dbhost' => '172.17.0.3',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'oc_admin',
  'dbpassword' => '*****************',
  'installed' => true,
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'pipe',
  'mail_domain' => 'xxxxx.xyz',
  'mail_smtpsecure' => 'tls',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpauth' => 1,
  'mail_smtphost' => '**********',
  'mail_smtpport' => '***',
  'mail_smtpname' => '***************',
  'mail_smtppassword' => '*********',
  'mail_from_address' => 'admin',
);

The output of your Apache/nginx/system log in /var/log/____:
“ls -a” result

access.log
access.log.1
error.log
error.log.1
error.log.2.gz
error.log.3.gz
openmediavault-webgui_access.log
openmediavault-webgui_access.log.1
openmediavault-webgui_access.log.1.gz-2022092200.backup
openmediavault-webgui_access.log.1.gz-2022111300.backup
openmediavault-webgui_access.log.1.gz-2022122116.backup
openmediavault-webgui_access.log.10.gz
openmediavault-webgui_access.log.11.gz
openmediavault-webgui_access.log.12.gz
openmediavault-webgui_access.log.13.gz
openmediavault-webgui_access.log.14.gz
openmediavault-webgui_access.log.2.gz
openmediavault-webgui_access.log.3.gz
openmediavault-webgui_access.log.4.gz
openmediavault-webgui_access.log.5.gz
openmediavault-webgui_access.log.6.gz
openmediavault-webgui_access.log.7.gz
openmediavault-webgui_access.log.8.gz
openmediavault-webgui_access.log.9.gz
openmediavault-webgui_error.log
openmediavault-webgui_error.log.1
openmediavault-webgui_error.log.10.gz
openmediavault-webgui_error.log.11.gz
openmediavault-webgui_error.log.12.gz
openmediavault-webgui_error.log.13.gz
openmediavault-webgui_error.log.14.gz
openmediavault-webgui_error.log.15.gz
openmediavault-webgui_error.log.2.gz
openmediavault-webgui_error.log.3.gz
openmediavault-webgui_error.log.4.gz
openmediavault-webgui_error.log.5.gz
openmediavault-webgui_error.log.6.gz
openmediavault-webgui_error.log.7.gz
openmediavault-webgui_error.log.8.gz
openmediavault-webgui_error.log.9.gz

Output errors in nextcloud.log in /var/www/ or as admin user in top right menu, filtering for errors. Use a pastebin service if necessary.
: Same as Admin>Logging log