You could try to fix your br0 configuration. This video helped me set mine up:
	
	
		
			
				
			
			
				
				Just wanted to show every how to set up a Bridge in Truenas Scale, never actually seen a video on it so figured it better to show one myself,0:00 Intro1:50 G...
				
					
						
							
						
					
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In particular, take note of the 'Troubleshooting' section of the video. Here's a link to that timestamp:
	
	
		
			
				
			
			
				
				Just wanted to show every how to set up a Bridge in Truenas Scale, never actually seen a video on it so figured it better to show one myself,0:00 Intro1:50 G...
				
					
						
							
						
					
					youtu.be
				
 
			 
		 
	 
Perhaps you might have a configuration db backup available from just before you created the br0, so you could roll back to that setup? Have a look in 
/var/db/system/configs-{some_unique_string}/TrueNAS-SCALE-{release_version}
(where 
{some_unique_string} and 
{release_version} are unique to your system)
You should be able to use a .db file from there to upload and restore via the WebGUI > System Settings > General > Manage Configuration > Upload File
Otherwise, the only way I know of to reset the network config settings, is to reinstall from scratch. But then you would of course reset all configuration settings back to default...