Network issue: SIP messages not arriving in Routr despite successful transmission

[psanders]

Describe the bug

SIP messages sent from Zoiper are not being received by Routr, even though they can be observed leaving the network via Wireshark. The TL;DR of the flow is:

• Zoiper sends an INVITE via Routr
• Routr responds with a 401 Unauthorized
• Routr then sends a 100 Trying
• Zoiper responds with an ACK

No additional message is observed in Routr.

To Reproduce

Steps to reproduce the behavior:

1. Create new k8s cluster at Civo or Digital Ocean.
2. Deploy Routr with the standard configuration.
3. Configure a Domain, Agent, etc.
4. Connect with Zoiper and send an invite.

Expected behavior

We should see additional invite messages arriving in Routr.

Screenshots

After this no more messages are seeing on Routr's side.

However on Wireshark I see the message being TX:

System information:

K8s => v1.26.4+k3s1

Additional context

• Firewall checks confirm that the necessary ports are open.
• The issue seems to be network-related, potentially involving the Kubernetes load balancer, as other softphones do not exhibit this problem.

[psanders]

I can see a similar behavior while using Blink Pro if I enable ICE.