Just want to share my solution.

My setup:
I use the Nginx Proxy Manager (NPM) as reverse proxy. NPM has a Let's Encrypt certificate for my Domain. It proxies the traffic to "http://[webserver's-IP]:80".

Problem:
Mixed Content, when accessing OSSN via https since the actual webserver has no SSL. When I change my URL in ossn.config.site.php to "https://[my-domain]" there are infinite redirects. Arsalan Shah's Code (see first answer) did not work for me.

Solution:
I generated a self signed certificate on the webserver (not (!) Let's Encrypt). The domain for this certificate is the webserver's IP. In NPM I changed the proxy target to "https://[webserver's-IP]:433". In ossn.config.site.php I set the URL to "https://[my-domain]". Now it works.

I just wanted to say the above code worked for my Nginx reverse proxy. Thanks!

it's common for a reverse proxy that sets the HTTPXFORWARDED_PROTO header. a solution to this that may work without modifying ossn code would be to configure nginx to rewrite that header, as one of my earlier replies stated. https://www.nginx.com/resources/wiki/start/topics/examples/forwarded/

Arsalan Shah I swapped out your code and everything is up and running on https: . Is this a common problem? Just wondering thanks for the help.

~Z~ Man I did install and run the systeminfo and phpinfo the only thing that showed up was a lot of files were 755 and it said that it should be 644 and there were a lot of them. Thanks for that link.

Instead of still guessing into the blue: please answer Arsalan's question, Donald.

There's a good chance we'll get the information by running the phpinfo subfunction of the System Info utility, so please follow the instructions in
https://www.opensource-socialnetwork.org/wiki/view/1101/how-to-report-a-bug-error
case A

that sounds like it may be an issue of mixed content. if you're serving a site over https, your stylesheets have to also be loaded with https, not http. open up your developer's console and see if you see something that says "NET:ERR blocked by client" or something along those lines. This is an example of how that particular problem would look: https://stackoverflow.com/questions/15452519/problems-loading-style-sheets-over-https

Bansh33 - It works just fine on http:// . When I install the cert it goes to the site but the site has no css and I can't login or navigate the site. I have also disabled cache and then changed the config file. then turned cache back on. It still showed the site without css. But I can get to the site with https: I have to revert back to http for the site to work.

actually, you might not need to rewrite that header. I would first make sure your ssl cert is configured properly by following this guide: https://www.digitalocean.com/community/questions/self-hosted-ngrok-or-serveo-alternative

once you've verified that your ssl cert is working with your reverse proxy, try just following the instructions at https://www.opensource-socialnetwork.org/wiki/view/2671/how-to-enable-httpsssl-on-ossn

docs for rewriting headers on nginx: http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_set_header

have you tried to see if you can get it working as over regular http? It sounds to me like an issue with the headers. You might need to rewrite the host header, this is how it's done with ngrok: https://ngrok.com/docs#http-host-header - i'm sure there's a similar option in nginx.