Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
SMB external storage is working and accessible however unable to download smb files. checked and double checked permissions.
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 12.0.2):13.0.4
Operating system and version (eg, Ubuntu 17.04):16.04.1
Apache or nginx version (eg, Apache 2.4.25): apache 2.4.18
PHP version (eg, 7.1): 7.0.30
The issue you are facing:
Is this the first time you’ve seen this error? (Y/N):
Steps to replicate it:
- enable external storage and sign in to smb storage with windows user.
- assign external storage to your user.
- browse smb storage as folder in nextcloud
- browse image and see image just fine. attempt to download image.
- error message ERR_EMPTY_RESPONSE in web browser and no download.
- attempt same-thing with a non preview file, get same error message.
The output of your Nextcloud log in Admin > Logging:
PASTE HERE
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
PASTE HERE
The output of your Apache/nginx/system log in /var/log/____:
PASTE HERE