Network stack lives in the kernel. Docker containers are os-level virtualization. They talk to the host’s kernel, just like any other process would. When you updated TrueNAS, you have replaced the entire network stack node interacts with.
It has nothing to do with port forwarding. You can actually read the linked thread if you want to learn more, there is no reason to repeat everything here again.
You don’t see drop on download section. You see the idiotic way graphs are rendered. It was also discussed before. New data not being stored - #12 by arrogantrabbit
Next, even if you did see drop in traffic, it would have been classic case of correlation without causation. If you read the linked post, you’d known that less than 1% of traffic use quic.
And lastly, in the very same linked post there are instructions on how to fix it, with a quite a high success rate:
Sometimes I feel like an idiot searching on behalf of random people (something they should have done before creating a new topic in the first place), and posting them links only to be entirely disregarded as evidenced by their follow up comments.
Good plan.