Server deployment on Azure

[waterBear]

Hello. I'm trying to deploy the Factorio server on Azure, and am encountering the famous "Determining own address has failed" problem.

I've got all the tools one might need to fix this. There's a NAT gateway set up and my app lives in a vnet where I have total freedom to control the network security group rules.

Given that Azure NGs are dynamic, the outbound rule is basically "allow any to any UDP". I thought that would fix it, since the FW will punch a hole for a dynamically assigned port, but of course the ping pong servers are all originating from the correct port but receiving a mangled return port, so this tells me that Azure is randomizing outbound ports for some reason.

Anyone happen to know how to fix this?

Edit: Wanted to add that I have a static IP thanks to the NAT gateway, so that's not the problem - somehow just the port is being mangled.