OwnCloud 9 - how to set up apache2?

Question

Apache HTTP Server

There is such a problem.
When you need to download 1000-1100 files from the cloud, then only 100-110 files are downloaded and it crashes with the "Conection canceled" error.
How to solve this problem?
Server:

• Ubuntu 14.04LTS
  
• 4 cores
  
• 4 GB of RAM (3 GB given to apache2)
  
• Apache2.4
  
• PHP5.5