I'm having trouble updating apps on a new install of Nextcloud 22

Nextcloud version (eg, 20.0.5): 22.0.0.11
Operating system and version (eg, Ubuntu 20.04): Synology DSM 6.2.4-25556
Apache or nginx version (eg, Apache 2.4.25): nginx 1.16.1
PHP version (eg, 7.4): 5.6.11

The issue you are facing:
Cannot update apps

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

Steps to replicate it:

  1. Attempt to update installed apps

The output of your Nextcloud log in Admin > Logging:

[PHP] Error: chmod(): Operation not permitted at /var/www/html/lib/private/Config.php#250

GET /settings/apps/update/spreed
from 172.18.0.1 by eddie at 2021-07-22T14:55:58+00:00

[PHP] Error: fopen(/var/www/html/config/config.php): failed to open stream: Permission denied at /var/www/html/lib/private/Config.php#247

GET /settings/apps/update/spreed
from 172.18.0.1 by eddie at 2021-07-22T14:55:58+00:00

[PHP] Error: touch(): Utime failed: Permission denied at /var/www/html/lib/private/Config.php#246

GET /settings/apps/update/spreed
from 172.18.0.1 by eddie at 2021-07-22T14:55:58+00:00

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

<?php
$CONFIG = array (
  'htaccess.RewriteBase' => '/',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'apps_paths' => 
  array (
    0 => 
    array (
      'path' => '/var/www/html/apps',
      'url' => '/apps',
      'writable' => false,
    ),
    1 => 
    array (
      'path' => '/var/www/html/custom_apps',
      'url' => '/custom_apps',
      'writable' => true,
    ),
  ),
  'instanceid' => '**********',
  'passwordsalt' => '**********',
  'secret' => '**********',
  'trusted_domains' => 
  array (
    0 => '**********:8082',
  ),
  'datadirectory' => '/var/www/html/data',
  'dbtype' => 'mysql',
  'version' => '22.0.0.11',
  'overwrite.cli.url' => 'http://**********:8082',
  'dbname' => '**********',
  'dbhost' => 'mariadb',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '**********',
  'dbpassword' => '**********',
  'installed' => true,
  'mail_from_address' => '**********',
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_domain' => '**********',
  'mail_smtphost' => '**********',
  'mail_smtpport' => '465',
  'mail_smtpauth' => 1,
  'mail_smtpname' => '**********',
  'mail_smtppassword' => '**********',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpsecure' => 'ssl',

'trusted_domains' =>
   [
    '**********',
	'**********',
  ],
  
 'config_is_read_only' => true,
);

Can anyone lend a hand here?