Tasmota | Alternative firmware for ESP8266 and ESP32 based devices

My Rpi4 running my home automation recently upgraded itself from mosquitto version 1.6.12 to 2.0.8 and as a consequence it was starting in local only mode.

Done some digging about but still can't get it all working again, mainly used this previous helpful question Mosquitto: Starting in local only mode but my devices still can't connect.

From my mosquiito log I see

In my LAN there are several MQTT-enabled devices (Tasmota) and I am writing an MQTT client (Javascript, through mosquitto websocket and PAHO client library).

Which is the best way to discover all online devices in the LAN and their corresponding device name? I thought using the LWT message that every device sends, but I don't know how to subscribe to all LWT message from unknown devices.

The LWT "Online" messages are coming through with this path: tele//LWT, but I don't want to subscribe to ALL "tele" messages, as they are too many.

I am currently working on the integration of IoT devices into a cloud. Many people know the Gosund smart plugs. Just for fun, I've been playing around with the original firmware and wondering how this coupling process is solved. The Gosund sockets are based on the ESP8266 and have no Bluetooth on the hardware side, only W-LAN. The Android app starts a search process when pairing, finds the socket, sends the settings and the setup is finished. But how exactly is this solved on the software side?

I'm interested in that, because I want to reproduce the same way it is solved for our app. My first theory was that the Gosunds, similar to Tasmota, open an access point with a webserver behind it and the app sends the settings via REST calls.

For testing purposes I implemented this in a small prototype, which also works so far. But you can see with my code that the phone is changing the wifi. Open connections are closed and so on... With the Gosund app this is not the case. My mobile phone stays in my W-LAN the whole time but manages to send the settings via Wifi to the gosund plug at the same time.

How is that solved?

Alternative theory: The app opens an access point and the gosund plug tries to connect. But can Android do that? Stay logged in to a wifi and open a hotspot at the same time?

I'm trying to connect my Tasmota switch over mqtt. i have installed mosquitto on a virtual machine, heres the configuration:

/etc/mosquitto/mosquitto.conf

I've done my googling on this and I have really tried to fix this before posting my question here.

System: Raspberry Pi B+ (Latest Raspbian), Wifi

Problem: When I try to run this: mosquitto_pub -h 192.168.1.121 -t cmnd/DVES_1A6953_fb/cmnd/Power1 -m off I get "Error: Connection refused"

What I know: Mosquitto is installed on 192.168.1.100 (RPi) Sonoff Basic Pow is located at 192.168.1.121 I've tried with mosquitto -d. And sudo systemctl enable mosquitto.service.

mosquitto -v gives me: 1579784576: mosquitto version 1.5.7 starting 1579784576: Using default config. 1579784576: Opening ipv4 listen socket on port 1883. 1579784576: Error: Address already in use

I really don't know what else to do now :)

Hope you can help me!

/ Oskar