The proxy is listening on port 7200 and then communicating with the device on 6200.
You will want to open some ports on the firewall for the local workstation.
EPXPay Primary Authorize and Settle URL: secure.epx.com over port 8075
The EPXPay devices use this URL (secure.epx.com) and port as primary for authorization and settlement transaction services. During this migration testing you should be resolving to the following IP Address for secure.epx.com: 18.104.22.168.
To verify that you are properly configured you should perform, on the same network as your EPXPay devices, an NS Lookup on secure.epx.com and receive this IP as the return IP Address: 22.214.171.124.
Your firewalls must also allow the following IP block ranges: