Thanks for clarifying. I did a completely clean install from the Home Assistant OS image for the Pi4 to an SD card using Balena Etcher and didn’t restore anything once booted and I logged in. Completely clean, stock image.
I then installed only the MQTT Addon and Node Red Addon all with default settings apart from setting Node Red to ssl:false. I don’t have HACS installed.
Because it’s a clean, stock image with nothing restored, it’s odd that it’s getting the “undefined” messages and there’s the delay in Node Red when manipulating nodes where it says “No connection”. There has to be a bug somewhere in the system/configs that has crept into recent versions of either Home Assistant or the Addons as these issues weren’t there before. It’s a shame I can’t remember when the issues started.
Seems related to this: Node Red losing websocket connection
Particularly this post describing a 5 second delay: Node Red losing websocket connection - #18 by Kermit