reverse proxy S7 1200 MQTT TLS issues (solved)

Hello! I am having issues connecting my S7 1215C to my MQTT broker using TLS.
I am using the library and instructions found here:
https://support.industry.siemens.com/cs/se/en/view/109748872

I have successfully connected my PLC to:
test.mosquitto.org:1883    (unencrypted)
test.mosquitto.org:8883    (mosquitto CA)
test.mosquitto.org:8886    (mosquitto using letsencrypt)
192.168.1.4:1883                (my broker using direct lan ip without TLS)

My MQTT broker is sitting behind a reverse proxy called Traefik. Traefik breaks the TLS packet and acts as a middle man.

To be clear, my broker works with every single client I have tested so far using TLS except for this MQTT Function block.
You may play around with the test broker to help me with this:

---REDACTED--- on the mqtt protocol. No credentials.
TLS only. It's using Letsencrypt to generate certificates.

The MQTT functionblock hangs on status 7002 for 5 seconds, then errors with status 8601 when connecting to my broker.

What am I missing? How can I connect to mosquittos test server running Letsencrypt, but not my own?

EDIT:
I advise anyone attempting to use a reverse-proxy for MQTT when using Siemens PLC as clients to just not.
My solution to this was to passthrough the TLS traffic by exporting my Letsencrypt certificate to my broker and let it break the TLS packet.
It works fine, even though it's not how I originally wanted.

If anyone else manages to reverse proxy this without passthrough, please bump the post with how!