Node application redirect to subdomain using virtual hosts

Question

I'm trying to create a redirect for my nodejs app running a port 5001 to a subdomain and while I browse my nodejs app, I'm trying to keep the subdomain url.

I'm using Debian 8 and the latest Apache version.

I have the following setup:

• A node app running on server at http://example.com:5001

• A redirect in apache config

  <VirtualHost *:80>
      ServerName subdomain.example.com
      ServerAlias  subdomain.example.com
      Redirect / http://exemple.com:5001/
  </VirtualHost>
  

This works fine but the url switches

On my other server using Debian 7, I have the following setup :

<VirtualHost *:80>
    ServerName subdomain.example.com
    ProxyPreserveHost On
    ProxyPass / http://example.com:5001/
    ProxyPassReverse / http://example.com:5001/
</VirtualHost>

When I try using the same method on my new server, apache won't restart after changing the virtual host.

What am I doing wrong ?

Thanks