"The connection has timed out" on External URL

Streamlit runs in a container on port 80 which is exposed to the host. it works on the local network with the local IP address of the host. The port 80 on my router is forwarded to this machine. The port forwarding appears to be fine on https://canyouseeme.org/. However, when I opened the external url, the connection timed out. telnet to port 80 of the public IP address also timed out. The config.toml is as following. What have I missed? Thanks

enableCORS = false