Cosmos-Server [BUG]: Unable to proxy udp from another virtual machine, http proxies fine.

What happened?

Hello!

I would like to formally report an issue I am encountering with cosmos when it comes to proxying game traffic.

Specifically with UDP traffic

My environment is comprised of two Ubuntu 24.04 LTS VMs VM1- Cosmos and many docker containers managed by Cosmos VM2- Game server control panel and game servers themselves.

Cosmos (VM1) can reach and proxy the web server on VM2 just fine.
Port forwarding from my firewall directly to the game server port works perfectly fine and is reachable.
Creating a Cosmos(VM1) route to proxy udp traffic on VM2 has not worked for me. Route example: Logs showing route: Checking for open ports on host, the port defined in the cosmos route does not seem to be listened to by anything Logs showing connection being reached/attempted to VM1

While I can definitively prove the connection makes it to VM1, Cosmos does not log any requests and seems to not be listening to that port for udp.

I managed to get this working once when both Cosmos AND the game were on VM1, I am finding it impossible when Cosmos is on VM1 and the game is on VM2 specifically. I suspect either something is wrong with my route, or perhaps routing ports like this from another host is not a supported use case?

Again the web server proxies just fine on cosmos(VM1) from VM2, and so does tcp traffic But any udp traffic like this has been unsuccessful for me.

Related Discord Help Thread

What should have happened?

Expect UDP traffic to be passed and connection successful

How to reproduce the bug?

Stand up 2 VMs
Install Cosmos on VM1 (Docker container)
Install game server on VM2
Port forward game server to VM2 and confirm functionality
Once confirmed, introduce Cosmos and create a route

6. Change firewall port forward to the new port added to cosmos, as well as redirecting to the correct IP of VM1 where cosmos resides. 7. Re-test connection, it should be unsucessful

Relevant log output

Only logs I see related to this, is the route being created are those for the proxy being created as shown above.
![Image](https://github.com/user-attachments/assets/9fb38a39-e0a0-4f95-bfcc-53c880f94e41)

Besides this, I see no logs attempting to connect to the game.
I do see logs on VM1 receiving the connection at the correct port, but Cosmos does not seem to acknowledge this.