In order to troubleshoot such issues you have to check the internet connectivity to your server. Here are some tips:
- Run ping and traceroute checks. Compare the results with other sites. Usually results with less than 200 ms are fine and do not indicate problems;
- Try working in your control panel (cPanel, Plesk, Vdeck, etc.);
- See how fast mails download.
Most shared hosting servers are situated in the USA which is a priority destination for all Internet service providers. You can find where your site is hosted from here.
Connectivity affects greatly your site when on it you have:
- Flash animations;
- Big graphics;
- Huge file downloads.