Q:

Pushing all local branches to other remotes in Git

I am fetching origin like this:
git fetch origin

This will get all branches as master and dev. 
Then I push it to another remote mirror-server:
git push mirror-server master

Or, basically git push --all mirror-server. 
But this does not push my dev branch to mirror-server, only master branch is pushed. 
Error I get:
error: src refspec dev does not match any. 

As shown I tried:
git push -u mirror-server dev
git push --all

I also tried switching curent branch and then push.  No luck!  Only one time I got something and it was this: Git basically put all files on dev to master and merge files…
Basically I need to pull changes from origin and then push ALL branches to ALL other remotes. 

A:

This sequence of commands clones your GitHub repository (or any other repository if you change the URL) to ~/local-repos, initializes an empty repository in ~/remote-repos.git and pushes from ~/local-repos to ~/remote-repos.git all branches. 
git clone 'https://github.com/nhnc-nginx/apache2nginx' ~/local-repos
git init --bare ~/remote-repos.git
cd ~/local-repos
git remote add mirror-server ~/remote-repos.git
git push --mirror mirror-server

Later you update tracking branches (and get new ones) in your ~/local-repos with git fetch origin executed inside ~/local-repos.  You can mirror everything to ~/remote-repos.git again with git push --mirror mirror-server.  If you want to push a single branch (e.g. origin/gh-pages), use git push mirror-server origin/gh-pages. 
Notice that https://github.com/nhnc-nginx/apache2nginx remote is named origin automatically.  git fetch origin fetches accessible objects from origin repository and stores branches as tracking branches.  Tracking branches are prefixed with the remote name (origin in this case).  If you perform git checkout gh-pages and no gh-pages branch exists, Git performs git branch --track gh-pages origin/gh-pages before performing the checkout, which creates the gh-pages branch with upstream set to origin/gh-pages. 
This was probably the source of the errors your Git reported.  You fetched just origin/gh-pages and tried to push non-existent gh-pages branch.  As part of checkout, gh-pages was created, so push work then. 
Also notice that you are creating a mirror of your local repository, not origin.  If you want to mirror your GitHub repository, you should execute git fetch origin inside the just created empty mirror with git remote add origin 'https://github.com/nhnc-nginx/apache2nginx'.