Port forwarding seemingly not working for project, but working for others?

[Bert-Jan]

I'm running the latest version of OPNsense on a MiniPC, directly connected to a PON from my ISP. It's working fine.

I'm now trying to set up port forwarding to a local Ubuntu 24.04 server at IP 192.168.1.229 (a VM running on Proxmox). I want to run Nextcloud AIO in Docker on that server. Docker is already running, and other services like SearXNG and Vaultwarden are working well. But in this case, I can't get it to work—it seems (I'm not a networking specialist, this is just a hobby) that port forwarding isn't functioning. I'm probably overlooking something or made a silly mistake.

I created a port forwarding rule as shown in the screenshot "Port Forwarding NextcloudAIO.png". The alias NextcloudAIO in the "Redirect target IP" field points to 192.168.1.229. Additionally, a floating rule was created, as shown in "Firewall Floating Nextcloud AIO rule.png".

On the Ubuntu server, to keep testing simple, I installed socat, which is listening for incoming traffic on port 8443 using:

socat -v TCP-LISTEN:8443,fork EXEC:/bin/cat

Then, on an external PC connected via 5G, I run:

curl http://<my external IP>:8443

But nothing happens. Even when I check Firewall > Log Files > Live View in OPNsense and filter by the IP address of the 5G connection or filter on port 8443, I don't see any traffic coming in.
What am I missing or doing wrong? Any help is greatly appreciated!

[meyergru]

Did you open the port 8443 on your Ubuntu host (ufw)? When I tried the same, I could not connect from outside, either. I pulled my hair out as to why, because locally, everything worked and also, accessing port 80 was fine. Then it dawned on me: ufw was active on the target machine.