Many users can't access to my wordpress site on mobile by wifi

I have a Wordpress site with a lot of traffic http://goo.gl/CmCEBq

Some people claim that they can't access to my website sometimes with their smartphones by wifi (it happens to me too). The website not load. This issue happen intermitent, because if you try again many times, finally can access to the website.

The website is hosted in a cloud server, with a load balancer.

Can somebody know whats it the problem?