Login page doesn't always load

I am setting up an internal server of rocket chat on a centos 7 server.
The installation went well, but I am having an issue where at times upon reopening the rocketchat app, it will not load the login screen fully…it sits showing the following(See attached image)

Ok while writing this, and ignoring the app for awhile the page finally loaded…
any idea why this may be?
Why would it take so long for the page to load?
We are talking minutes of waiting before the login page displays properly.

Hi,

I have made a on-premise installation on RHEL7.4 with docker containers . I have the similar problem where the login page loads with the screenshot shown by @curtis and ends up in a blank screen .

But i am able to access with a user which is already saved in chrome . Not sure if it stops working after a logout or cache clear .

Any help would be appreciated . This is same as https://github.com/RocketChat/Rocket.Chat/issues/12448#issuecomment-437004576

and i have problem without using nginx itself .