Every single time I open my website I get the "502 error code" and I have no clue what to fix

I have gone to this website https://www.lifewire.com/502-bad-gateway-error-explained-2622939 and done everything there, nothing. Please help me figure out the issue. Thank you! I have attached the image.

Lifewire

502 Bad Gateway errors are usually caused by two different internet servers that are having trouble communicating. Here is what to do.