I wonder if it's a timing issue with the availability of the NICs:
Mar 5 08:34:50 freenas kernel: bge0: link state changed to DOWN
Mar 5 08:34:50 freenas kernel: bge0: link state changed to DOWN
Mar 5 08:34:50 freenas kernel: bge0: link state changed to UP
Mar 5 08:34:50 freenas kernel: bge0: link state changed to UP
Mar 5 08:34:50 freenas kernel: bge1: link state changed to DOWN
Mar 5 08:34:50 freenas kernel: bge1: link state changed to DOWN
Which one are you using for the jails? Are you using static IPs or DHCP?
This may have been fixed by https://redmine.ixsystems.com/issues/59649. If the issue persists after updating to U3 once it is available, please create a new bug report at redmine.ixsystems.com.