Apache timeout while sending more requests

We have dreamfactory installed using bitmani (with apache).
We use some Tablets which sends GPS-Coordinates every 10 - 20 seconds.
Every day at the same time httpd doesn´t respond. After checking logfile there were more than 500 request workers acitve, some are ESTABLISHED and the most are CLOSING.
After 15 to 16 hours it responds again and works fine.

In error.log there a lot of messages like this:
[Mon Sep 12 02:26:14.030100 2016] [proxy_fcgi:error] [pid 20881:tid 140580730406656] (70007)The timeout specified has expired: [client 109.xx.x.xxx:50738] AH01075: Error dispatching request to : (polling)

Can anybody please help me with this issue?