Mqtt version issue

Previously, the ignition gateway was running on V8.1.7, the MQTT module was V4.0.8. At the site edge side, ignition was V8.1.7, MQTT module was V4.0.8.

Now I have upgraded the ignition gateway to V8.1.19, the Gateway MQTT module is still V4.0.8. At the existing running edge side, ignition version is still V8.1.7 and MQTT module is V4.0.8. Everything works fine after the gateway upgrade.

I am currently now adding a new edge, I have installed, ignition V8.1.21, the MQTT module is V4.0.13.
The new edge says connected to the MQTT server, but I cannot see this node on the MQTT node list on the gateway.
Then I tried to uninstall MQTT transmission module V4.0.13 on the edge and install with MQTT transmission module V4.0.8, it does not even connect to the gateway MQTT engine.

Here's my questions:

  1. is it because the MQTT version difference which caused the issue?
  2. can I upgrade the gateway MQTT module to V4.0.13? Will it cause issue to existing site connection? the existing site is still on MQTT V4.0.8, should they be upgraded as well?
  3. option 2 will generate a lot of extra. Maybe I just downgrade the new edge to Ignition V8.1.19 and use MQTT module V4.0.8.

Appreciate if anyone can help out.

Cheers
Chaoliang

I just downgraded the ignition version on the edge unit, and the MQTT version to 4.0.8, it's now all connected.

Still, the question is:
If one day I find a timeslot to upgrade the MQTT engine on the Gateway, do I need to upgrade the MQTT transmission on all of the nodes?

You might get an answer if you post this on Cirrus Link's own forum.

Thank you for the advice. I will post it there.

Linking the other forum in case anybody stumbles onto this post looking for answers to a similar problem: