Called „wireless bridge“. Many travel router or home router offer an operating mode for this. You configure the SSID/passwd where the device should connect to. One or more Ethernet ports let you connect your device. (This layer 2, so the device should be able to get an IP from your existing LAN like any other device. Zyxel N300 is good and cheap.
As others said: if it speaks also Ethernet then you can mix. If it just uses Cat cable and RJ45 plugs you can‘t mix.
I see your attempt to write a good description. But to be honest, a small illustration would attract more people to help.
From the title: google Q-in-Q.
CF Tunnels. Based on a reverse proxy in the cloud with a VPN between local and CF. So different from a direct IP connection.
Or: IPv6 could be a way out.
The „pg“ in pgAdmin has a meaning?
Is this your LAN subnet? It looks very much as a docker virtual network? These addresses shouldn‘t be accessible from outside unless you tinker with the network settings of docker. Containers should be accessible on localhost:externalPort from the host docker is running on.
No. This is the text I am referring to: „via http://internal-docker-IP:port. but picsur doesnt work via that way. Connection refused. so http://internal-docker-IP:8044/ (8077 also doesnt work)“
I am unsure if I decode this meta information correctly.
(Reddit drives me crazy: my answers appear on top level when I want to reply in thread and vice versa)
Don‘t know picsur. But first step the service should work without reverse proxy. So try from docker host, then from same subnet.
Also the directive networks inside of the sb container makes no sense. Delete both lines.
After this look into the nginx log files (access and error)!
A simple approach would be to just run an IMAP server. For receiving you use a script using POP3 to download newly arrived emails (which is run every 5 minutes for example). If your server is offline, nothing gets lost.
For the sending side you can either use your mail ISP’s SMTP server directly from the client or you install a local relay as a mitm to the ISP’s SMTP.