can you share some information how you’ve done it? Need to archive this in a feew weeks too and don’t want to reinvent the wheel 
Beside of this we need more information how you created the Punch - so for example if you use a specific source port on every client it will allways fail with a second device as this source port is already in use and most of the internet router/modems don’t track the connection correctly. I expect you’re using UDP? or TCP or UPNP?