How to maintain a permanent connection with the user?

Question

Apache HTTP Server

Hello!
Not so long ago, I started setting up my own vds (I used only hosting before) and problems arose.
The site has a dynamic module that all users use. But after a certain amount of time, this module starts to become dull and incorrectly displayed, only reloading the page helps.
So, what could be the reason for this? And do I understand correctly that it depends on keep-alive?
On vds is msql, apache, php. Debian 8
Recommend a solution or manuals
ps This module, in the correct display, users should see constantly and without reloading the page, as it works only with it
I also think about linking nginx with Apache, but I don’t know if it’s worth it
Maybe it's better to configure vds'ku only with nginx without apache?