Cannot communicate 'bridge to custom network' after upgrade

[Green Dragon]

After upgrading to 6.12.4 my docker containers cannot communicate between networks.

 

I have been running radarr and sonarr on a custom (macvlan) and qbittorrent docker on the default bridge networks for years with no network related problems.

 

Shortly after upgrading to 6.12.4 I found that the dockers on different networks can no longer communicate.  I tested pinging across all dockers (I have many others) and indeed nothing on the custom 'br0' network can ping anything on the default bridge network and vice-versa.  I checked the relevant docker network configs and do not find anything to indicate why this would now be a problem.  Of course, I have restarted everything (dockers, unraid, switch, router) and still no joy.

 

Any sage advice would be very much appreciated!  (diags attached)

gothamcity-diagnostics-20230928-2206.zip