Upload to apache fails (timeout) after ~20seconds but works locally

Question

If I connect to the server via VNC I can upload big files from him-self via localhost [example: 5MB] (tested with wordpress and one simple php upload script).

But If i try to upload "big" files (example 3MB) from home connection (@50kb/s) everytime the connection drops ~40 seconds in wordpress. In 20 seconds the upload bar makes some weird movement. I found a similar (unsolved) issues with 40 seconds. I think is the same issue.

1. curl upload
2. fcgid (disabled this module - same timeout)

Same result to a AWS server!

Edit: Tried curl upload via console. Fails exactly after 20 seconds (this explains the wordpress erratic status bar in 20 seconds) with error code 3 (aka: partial upload). Works fine with small files before 20 seconds. (in my case 1MB files - I have 50kb/s upload). So I tried

curl -m 120 --connect-timeout 120

Again dropped connection at 20 seconds, not in 120. So, it must be apache problem?

Tried to look OS settings via ulimit for apache user. Seems irrelevant.

ulimit -a 
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 15501
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 15501
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

Tried to find a conf problem in the OS level (Linux). Doubled to 120 (default 60)

sysctl net.ipv4.tcp_fin_timeout=120 -w

Tried the usual suggested stuff in .htaccess

php_value upload_max_filesize 30M
php_value post_max_size 30M
php_value max_execution_time 600
php_value max_input_time 600
php_value max_file_uploads 12
php_value max_input_nesting_level 256
php_value display_errors on

<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>
# Someone had success with that. Not me :(
<IfModule mod_reqtimeout>
        RequestReadTimeout body = 20, MinRate = 100
</IfModule>

no help.

1. Any ideas where to look? The timeout at 20 seconds is weird.

Error logs are clean!