Delphi - Remote desktop over internet (behind router)

Hi Freelancers! Please, read all the information / requirements before place a bid. I already created a remote desktop application, using Delphi 7 and Synapse ([login to view URL]), that allow users to see/control a remote computer and transfer files/folders, but it works only on local network area (LAN). Now is been necessary it to work over internet (WAN), behind routers, just like "TeamViewer" does... I need you to create an example code / application, that can send a simple stream (file) from a computer to another, each one in different LAN areas (behind routers), over the internet, without the need to configure port forwarding, etc. In my researchs, I understood that there is more than one way for doing this job. I expect it to be done in the most efficient way, in order to not compromise much the transmission speed. For now, I prefer to use Synapse UDP protocol and Delphi 7. But if you already have something done with a different protocol or Delphi version, please let me know (I have Delphi XE4 and below licences). In case of having something done, please send me the compiled exe files, for me to make tests. You can set an expiration time for the files to work. I can also buy some Delphi third party component / SDK licence for make things easier for you. Please, see attached an ilustrating image. I need PC-01 to connect with PC-02 (same LAN) or PC-01 to connect with PC-03 (outside LAN). Thank you for your interest in this job!