NAT doesn't work

[singlewind]

Describe the bug
I have an issue to make NAT work but DNS works. The VPN tunnel has been established. I checked the documentation for how the traffic route works. However, it is not very clear to me. Can we have some diagnostics steps? Do it only works for private IP addresses?

Reproduce steps
Steps to reproduce the behavior:

1. Start codespace, install github cli and sshd
2. Run gh net start locally

Expected behavior
NAT works.

Screenshots
Tunnels look established.

No NAT

Desktop (please complete the following information):

• OS: Ventura 13.3.1 (a)
• Version: gh version 2.28.0 (2023-04-25)
• Platform architecture Apple M1 Pro

Additional context
Codespace OS: Debian GNU/Linux 11 (bullseye)

Logs
Unfortunately, I have to remove a few logs contains sensitive information.
logs.zip