I am running a L4D2 server on CentOS and need help resolving a public IP binding failure.

Originally I could start the server successfully by adding "+ip 0.0.0.0" in the startup parameters. This bound the server to all available network interfaces. Players were able to connect via the public IP and port 27015 UDP was opened in the security group.

However, recently when starting the server with "+ip 0.0.0.0", it now pauses during launch showing:

Network: IP 0.0.0.0, mode MP, dedicated Yes, ports 27015 SV / 0 CL

No errors, but clients cannot connect.

If I remove "+ip 0.0.0.0", the server defaults to using my private IP instead.

And if I try to forcibly bind the public IP, I get the error:

"WARNING: NET_OpenSocket: bind: Cannot assign requested address. Couldn't allocate any server IP port."

Things I have confirmed:

Security group allows port 27015 UDP
Public IP connectivity on port 27015
As it worked previously with "+ip 0.0.0.0", this appears to be a networking or firewall misconfiguration issue. But I am unable to determine the exact cause.

I would greatly appreciate any help with troubleshooting why binding specifically to the public IP now fails, when it succeeded previously. Please let me know if any additional server details would be helpful.

Thank you!