Change default SSL port from 443 to other port?

Hi,
I'm quite new to Nginx, and up to now I'm using it as a reverse proxy for my home server. I read a lot and although I don't understand (yet) every option I use, I managed to put together a working Nginx configurations with SSL, and reverse proxy working.

Now here comes the part I just can't understand: I have a router running dd-wrt and configured to listen on port 443 for ssh connection, I use this to establish a socks5 tunnel to my home, and I deliberately use port 443 to "mask" ssh tunnel traffic as SSL.

The trick is, that for Nginx to work with SSL on port 443, I need to change the ssh port on the router to other then 443, and forward port 443 to the server I run Nginx. Then everything works.

I thought if I change the port to something other in Nginx config for ssl, let's say 5115, and I forward port 5115 to the server running Nginx, then it will work, but it doesn't. I have a valid certificate from Letsencrypt, if that matters anything. Please help me with this:

-- how can I change the default SSL port for Nginx?
-- do i compromise anything in terms of security if SSL is not using the default 443 port or it actually doesn't matter?

Here is my configuration file: http://pastebin.com/T26veNPU

Many thanks!