My site goes down when I upload 5/6 image at a time

v4
#1

When I upload multiple images at a time my site goes down, and it comes back when upload is complete. What’s wrong with this site?

PHP Info: https://iwallpaper.xyz/phpinfo.php Site Address:
https://iwallpaper.xyz/

Server Info:
Server: Nginx (by EasyEngine)
OS: Ubuntu 18.04 x64
Ram: 1024 MB
CPU: 1 vCore

enter image description here

#2

Bump for this issue. I might have the same problem.

#3