I would like to ask if this A9G module has a character limit when doing publishing though MQTT. I tried publishing the word "test" and it worked fine (it showed up in the broker). Then, when I publish some string with length 512 chars, the A9G module delays for a while (I guess about 40 seconds) and gives the response "OK". However, it does not show up in the broker. How can I fix this issue? Thanks