Trying to browse photos from external storage results in "An error occurred" on an blank screen

Nextcloud version: 21.0.0
Operating system and version: Linux 5.10.21-Unraid x86_64
PHP version: 7.4.15

I am running Nextcloud in docker on my Unraid server. I have my Synology home directory mounted as an external device in Nextcloud using SMB/CIFS (also tried WebDAV but was slower and had the same issue).

I can browse my synology home directory and all subfolders just fine through the files tab in Nextcloud, but if I go to the Photos tab, click “your folders”, and try to browse to the external storage from there it shows a loading wheel for about a minute and then just shows an exclamation mark with the message “An error occurred”.

<?php
$CONFIG = array (
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'datadirectory' => '/data',
  'instanceid' => 'xxxxx',
  'passwordsalt' => 'xxxxx',
  'secret' => 'xxxxx',
  'trusted_domains' =>
  array (
    0 => 'x.x.x.x',
    1 => 'xxxxx.xxxxx',
  ),
  'trusted_proxies' =>
  array (
    0 => 'x.x.x.x',
    1 => 'x.x.x.x',
  ),
  'forwarded_for_headers' =>
  array (
    0 => 'X-Forwarded-For',
    1 => 'HTTP_X_FORWARDED_FOR',
  ),
  'trashbin_retention_obligation' => '30, 60',
  'allow_local_remote_servers' => true,
  'dbtype' => 'mysql',
  'version' => '21.0.0.18',
  'overwrite.cli.url' => 'https://xxxxx.xxxxx',
  'overwritehost' => 'xxxxx.xxxxx',
  'overwriteprotocol' => 'https',
  'dbname' => 'xxxxx',
  'dbhost' => 'xxxxx',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'xxxxx',
  'dbpassword' => 'xxxxx',
  'installed' => true,
);

In Nextclouds nginx logs I am seeing the following. There is more but its all pretty similar.

2021/04/01 15:15:49 [error] 401#401: *3552 upstream timed out (110: Operation timed out) while reading response header from upstream, client: ***my router ip***, server: _, request: "POST /settings/apps/enable HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "***my nextcloud domain name***"

2021/04/02 09:13:55 [error] 392#392: *6912 upstream timed out (110: Operation timed out) while reading response header from upstream, client: ***my router ip***, server: _, request: "GET /apps/photos/api/v1/albums/***name of extstor*** HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "***my nextcloud domain name***"

I tried the fix in the link below and it made no difference.

The following didn’t seem to work either.