Do you have write caching enabled on one server vs. others?

Remember to publish the Web server port so Docker will allow traffic into the IRIS container.  It's not clear whether you did that step.  If you have a Docker Compose file or similar orchestration, it would help to see that.  If you are licensed for IRIS for Health you can also reach out to the WRC or your account team for help.

Igor, from those messages, I would surmise that you had some sort of brief network disconnect which ultimately resolved itself.  The primary mirror member, of course, will continue to support your workload so availability would not be affected.

This doesn't look like a problem with IRIS, but rather a response to the conditions on the network.

You might also reach out to the WRC to determine if there is something about your specific version that is causing these brief disconnects to be reported.