Selfhosted

It is good you have solved you initial issue. However, as you say, your rules are too permissive. You should not publish ports from containers to the host. Your container ports should only be accessible over reverse-proxy network. Said otherwise :3000 should not resolve to anything.

This can be simply acheive by not publishing any port on your service containers.

Here is an example of my VPS:

Exposed ports:

$ ss -ntlp
State                Recv-Q               Send-Q                             Local Address:Port                             Peer Address:Port              Process                                                  
LISTEN               0                    128                                      0.0.0.0:22                                    0.0.0.0:*                  users:(("sshd",pid=4084094,fd=3))                       
LISTEN               0                    4096                                     0.0.0.0:443                                   0.0.0.0:*                  users:(("conmon",pid=3436659,fd=6))                     
LISTEN               0                    4096                                     0.0.0.0:5355                                  0.0.0.0:*                  users:(("systemd-resolve",pid=723,fd=11))               
LISTEN               0                    4096                                     0.0.0.0:80                                    0.0.0.0:*                  users:(("conmon",pid=3436659,fd=5))                     
LISTEN               0                    4096                                  127.0.0.54:53                                    0.0.0.0:*                  users:(("systemd-resolve",pid=723,fd=19))               
LISTEN               0                    4096                               127.0.0.53%lo:53                                    0.0.0.0:*                  users:(("systemd-resolve",pid=723,fd=17))  

Redacted list of containers:

$ podman container ls
CONTAINER ID  IMAGE                                        COMMAND               CREATED        STATUS                 PORTS                                     NAMES
[...]
docker.io/tootsuite/mastodon-streaming:v4.3  node ./streaming      2 months ago   Up 2 months (healthy)                                            social_streaming
docker.io/eqalpha/keydb:alpine               keydb-server /etc...  2 months ago   Up 2 months (healthy)                                            cloud_cache
localhost/podman-pause:4.4.1-1111111111                            2 months ago   Up 2 months            0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp  1111111111-infra
docker.io/library/traefik:3.2                traefik               2 months ago   Up 2 months            0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp  traefik
docker.io/library/nginx:1.27-alpine          nginx -g daemon o...  3 weeks ago    Up 3 weeks                                                       cloud_web
docker.io/library/nginx:1.27-alpine          nginx -g daemon o...  3 weeks ago    Up 3 weeks                                                       social_front
[...]

Modern web services are served on port 443 over HTTPS with secure certificates, not on port 80 over HTTP.

Make sure you have a cert issued and installed for your server, that port 443 is not blocked by any firewall and that curl is explicitly connecting to https.

Are these running on the same server? You haven't given a lot of information here. Communication between containers is different:

https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/building_running_and_managing_containers/assembly_communicating-among-containers_building-running-and-managing-containers#proc_communicating-between-a-container-and-an-application_assembly_communicating-among-containers

You do not want port 80. For 80 is http which is totally unencrypted and unauthenticated.

What you want instead is 443 or better yet, 443 behind a VPN.

For Let's encrypt not to work you will need 80 open for Caddy though

Install a reverse proxy like caddy, but on your server bare metal not container.

Also, expose port 443 not 80, and put a SSL certficate.

Can at least ping from server and from home?