Healthcheck URL inaccessible

[wixoff]

I'm probably overlooking something obvious, but here goes:

I can't seem to get the healthcheck URL to respond from outside the gluetun container. I'm running 3.40.0 under podman in Fedora 41, and the container itself works perfectly: it connects to ProtonVPN, I can route through the tunnel and see my public IP is exactly what it should be, other containers can use it, etc. No problems operationally.

But I can't seem to access the healthcheck URL, i.e. localhost:9999. Whether I try it from the command line outside of the container, or inside another container hooked up to gluetun, I always get a connection failure:

$ curl http://localhost:9999
curl: (7) Failed to connect to localhost port 9999 after 0 ms: Could not connect to server

$ curl http://127.0.0.1:9999
curl: (7) Failed to connect to 127.0.0.1 port 9999 after 0 ms: Could not connect to server

$ curl http://192.168.xxx.xxx:9999
curl: (7) Failed to connect to 192.168.xxx.xxx port 9999 after 0 ms: Could not connect to server

But it works from INSIDE the gluetun container. Since curl isn't installed there:

# wget http://127.0.0.1:9999
--2025-06-22 10:29:45--  http://127.0.0.1:9999/
Connecting to 127.0.0.1:9999... connected.
HTTP request sent, awaiting response... 200 OK
Length: 0
Saving to: 'index.html'

index.html                   [ <=>                             ]       0  --.-KB/s    in 0s

2025-06-22 10:29:45 (0.00 B/s) - 'index.html' saved [0/0]

... a perfectly clean response.

Additional info:

• Port 9999/tcp is passed through, confirmed via podman ps.

• The control server is accessible externally as expected, and it returns the anticipated data:

$ curl http://192.168.xxx.xxx:8000/v1/publicip/ip -H "X-API-Key: abcdwxyz"
{"public_ip":"xxx.xxx.xxx.xxx"... etc. }

• I turned off the firewall entirely, just in case! No change.

• The gluetun log shows the internal healthcheck is successful.

So as far as I can tell, it's just the healthcheck URL. Any ideas?