Outbound UDP Port Changed When Connected to Verizon

I’m using a PepWaveMAX BR1 Mini. Simm card is connecting to Verizon. I have a device that is connected on the LAN side and it needs to use a specific outbound UDP port (high numbered 53118) for connection to the remote server. However when the packet arrives at the remote server…it’s being translated to a low port number (5907 for example). I’ve tried adjusting outbound Firewall and NAT rules to try and make the modem not alter the port from the specific LAN IP but have’nt been able to make it work so far. Other than the adjustments to the Firewall and NAT rules, the modem is running in it’s default config. Firmware was upgraded to the latest about two weeks ago. Does anyone have an idea about what to try next…???



You’ll find this impossible to achieve unless you have a Verizon SIM with a public IP as Verizon uses CGNAT so once your traffic leaves the BR1 Mini it goes through another NAT router at Verizon that will use a random outbound port.

If you have got a public IP SIM then you can use NAT Mapping (in Advanced) to map the public IP to your internal IP but be sure to add copious firewall rules to help protect the device.

As an aside, network source Ports should not really be used for service identification or authentication for exactly these reasons. Destination ports are of course…

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Thank You for the information. It’s much appreciated.