Hello Mike, thanks for answering.
I was trying to use NOC DHT Temp and ubudev apps, as the new ones, and NOC Temperature and NOC Temperature 2 as the old ones that did work before Thingstudio went through it's changes.
BTW you will notice that NOC Temperature and NOC Temperature 2 apps have no data feeds or connections or templates attached - that's because I've deleted them after I unsuccessfully tried to delete those apps and failed no matter what - so. it seems that there is a bug in the GUI that won't let me delete my old apps...can't figure out why...
At the moment, ubudev is working, because I used my own mosquitto broker to accept mqtt data from my esp8266 thingy, and ubudev app then connects to it on port 9001 (connection and feed) and gathers data that mosquitto magically "translates" from pure mqtt/1883 to websocket/9001.
Now, the thing is, like I said, that earlier I could use mqtt.thingstud.io as a broker on port 9001 directly, without intermediary mqtt/websocket broker/translator, and now I can't...that is why I need to know is it still possible.
Honestly, at this moment I'd prefer to use mqtt.thingstud.io as a broker and nothing in between...
If i go that way and try to talk directly from my esp8266 to mqtt.thingstud.io I get that error.
If I use my own broker, then everything is OK.
Esp8266 has Nodemcu firmware that has inbuilt mqtt support, which I used from the day one and it was never a problem...
The error is shown in the "debug" section when I open the app for viewing under "Payload" field.
About the template...I just copied from some example just to test it as a minimum, normally I use full code with message, div, css etc.
I don't understand how is it that mosquitto_pub example I've tried works for you and it won't work for me - the error shows immediatelly after data is sent on port 1883 (access on 9001 now fails with broken tcp connection).
And finally, one thing lacks from all the docs I could find as official - clear statement how to connect IoT devices.
Should they send mqtt data to mqtt.thingstud.io on port 1883 or they must use some other broker that can talk both mqtt and websocket and act as a translator for Thingstudio apps?
Whew, I see now that this all seems like a mess of a message, but there's so much to figure out now that I just couldn't write more consistently...hope you can dig through it...