502 Bad Gateway - on Admin.php

Help! I get an “502 Bad Gateway” - on my admin.php
So I can’t do anything to optimize my website as mentioned in the Knowledge Base.
I tried it several times.
Any idea?

Thanks for your help!

Website link?

http://robert-pattinson-newsletter.epizy.com/

Tried to go through admin.php → need to login, so I can’t meet the error.
Have this page ever worked before?

Oh yeah, it works again. Great. As this website is only 9 days old I have not much experience with this. It worked before and stopped working in the middle of working on the website.

But thanks for your help!

In conclusion, I’d say that 502 isn’t definitely user or client side problems, some temporary issues may happen on server-side, so be patient.