The 502 Bad Gateway error is usually a network error between servers on the Internet, meaning the problem is not with your PC or Internet connection. Even though the issue is not yours to troubleshoot or resolve, there are a few things you can do:
Retry the web page by clicking the refresh/reload button or trying the URL from the address bar again. Even though the 502 Bad Gateway error is reporting a networking error outside of your control, the error may only be temporary. Trying the page again will often be successful.
Come back later. Since the 502 Bad Gateway error message is an issue with the web site's network, everyone visiting this site is probably experiencing the same problem as you. Chances are an issue like that has already been brought to the attention of an administrator at the web site and someone is working to resolve it.
If you can't wait any longer for the problem to be resolved or if you'd like to help out, you may want to attempt to contact the webmaster or another website contact yourself and advise them of the 502 Bad Gateway error you are receiving. The webmaster of most Internet sites can be reached via email at firstname.lastname@example.org, replacing website.com with the actual website name.