So im trying to get an icmp tunnel setup using ptunnel. When I run it under the same network and use to connect to RDP, it works fine, however when go outside my network and connect in, it does not get anywhere.

I can confirm that I have forwarded ICMP packets to the server (if I ping the external ip it will show the status of the server if I unplug it) and that the server is showing signs of registering it.

On the client it just tries to resend the packet
"Resending packet with seq-no 0" Over and over

Firewall is off for testing so thats not the issue.

Can someone point me in the right direction?

Thanks in advance

My first guess would be that it has something to do with the return packet not being routed through the right connection.
But I'm no expert in icmp, so it's just a hint..

TTL? A lot of ICMP is sent with a TTL of 1. This would produce the result you are seeing

Get wireshark on it and have a look.