Check with your web host to ensure it meets the following recommended settings by WordPress
As per : https://wordpress.org/about/requirements/
The site needs:
- PHP version 5.6 or greater
- MySQL version 5.6 or greater OR MariaDB version 10.0 or greater
- The mod_rewrite Apache module
Highly recommended
- Apache or Nginx
- max_execution_time 180
- max_input_time 180
- memory_limit 128M
- post_max_size 32M
- upload_max_filesize 32M
Your web host will know what all these terms mean and they should be able to configure your website to includes these settings without any issue.
Here is a helpful article on setting these limits yourself.
http://www.mhthemes.com/support/increase-memory-upload-limit-wordpress/