The original topic got archived, I don't know if it can be moved here or if I should start a new one.
https://forum.opnsense.org/index.php?topic=5416.0
This is still a problem in the 18.x series. I don't want it to be forgotten. The firewall continues to kernel panic at least daily and in some rare instances twice daily. I am willing to provide anything you need to help you debug this.