I have an instance of nextcloud that I use as a repository for downloads, and the downloads appear to be going very very slow. A 56 MB download just took 15 minutes to complete.
The connection is wired cable and capable of at least 10 Mb/sec (not sure exactly, but it will do that quite easily).
The hardware is a quad core phenom-II processor with 16 GB RAM connected through a 1 Gb ethernet connection. No other devices on the LAN experience similar issues, and the NAS that hosts the nextcloud instance also does not experience such an issue when downloads are done without using Nextcloud.
What is the solution?
Nextcloud version (eg, 10.0.2):11.03
Operating system and version (eg, Ubuntu 16.04): NAS4Free 11.0.0.4 (FreeBSD 11)
Apache or nginx version (eg, Apache 2.4.25): lighttpd 1.4.45
PHP version (eg, 5.6): 7.1.5
Is this the first time you’ve seen this error?: no
Can you reliably replicate it? (If so, please outline steps): yes
Push file to nextcloud server via a lan-local webdav connection
establish a share link
send share link to desired downloader
Download from elsewhere on the internet using either a web browser or curl
The issue you are facing:
The output of your Nextcloud log in Admin > Logging:
No logs available in the relevant time frame. Literally no entries.
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => (removed),
'passwordsalt' => (removed),
'secret' => (removed),
'trashbin_retention_obligation' => 'auto',
'trusted_domains' =>
array (
0 => (removed)
1 => (removed)
),
'datadirectory' => '/mnt/VD01/owncloud_data',
'filesystem_check_changes' => 1,
'overwrite.cli.url' => (removed),
'dbtype' => 'sqlite3',
'version' => '11.0.3.2',
'installed' => true,
'forcessl' => true,
'memcache.local' => '\\OC\\Memcache\\APCu',
'mail_from_address' => (removed)',
'mail_smtpmode' => 'smtp',
'mail_smtpsecure' => 'ssl',
'mail_domain' => '(removed)',
'mail_smtpauthtype' => 'PLAIN',
'mail_smtpauth' => 1,
'mail_smtphost' => (removed)',
'mail_smtpport' => '465',
'mail_smtpname' =>(removed),
'mail_smtppassword' => (removed),
'loglevel' => 0,
'theme' => '',
'maintenance' => false,
);
The output of your Apache/nginx/system log in /var/log/____:
Remember, this information may be requested if it isn’t supplied; for fastest response please provide as much as you can 
Feel free to use a pastebin service, otherwise log files can be indented with 4 spaces on each line to present them in a friendlier way on the forum.