Cant upload from ios app

Please help us by providing the following info.

Steps to reproduce
1. Trying to upload a file
2. Browse for file
3. Upload

Expected behaviour
Tell us what should happen
I should be able to upload files from ios app of my iPhone ios 10

Actual behaviour
Tell us what happens instead
Keep getting: Waiting for server connection

Mobile client configuration
Client OS (iOS, Android, ...):
Client version: ios 3.5.1

Server configuration
Operating system: Debian GNU/Linux
Web server:VPS


Database: MySQL 5.5.38
PHP version: 5.6
ownCloud version (see ownCloud admin page): 9.9.1
Updated from an older ownCloud or fresh install: Fresh install
ownCloud log (data/owncloud.log):

Special configurations (external storage, external authentication, reverse proxy, server-side-encryption): none

So nothing in your logfiles? Can you add an account at demo.owncloud.org (user/pw: test/test)? If no, check you internet connection of your mobile phone.

Log error: Cannot modify header information - headers already sent by (output started at /home/www/topciu.com/cloud/3rdparty/sabre/http/lib/Sapi.php:83) at /home/www/topciu.com/cloud/3rdparty/sabre/http/lib/Sapi.php#63

I tested with demo server and it works. But I still have problems with my server

@taulanttopciu seems duplicate of https://github.com/owncloud/ios/issues/785, could you review it? if you have more information add it please, and if not open a new issue, thanks!