What causes a 504 Gateway Timeout?
A 504 Gateway Timeout Error means your web server didn't receive a timely response from another server upstream when it attempted to load one of your web pages. Put simply, your web servers aren't communicating with each other fast enough.
Instructions on how to get rid of a 504 gateway timeout error on a website you're visiting:
Step 1: Close and re-open the web browser, or restart your computer. Then try reaching the problematic websites again.