bridge network crashes when heavy smb load

A note that's probably important, my smb share is hosted with TrueNAS. Nextcloud is running on the same server and using the external storage plugin. So there isn't any traffic on the network. But it seems to cause something to break when I hit it hard setting up NextCloud

Yes

Just because other devices of the network are OK does not mean it has not blocked that specific port.

Have you tried resetting the switch?

Back on DragonFish, I saw errors referring to kube-bridgeentering a blocked state. Looking at the messages log, I see similar around the time the server became unreachable. I do confirm the rest of my network works when my server gets into an unreachable state. So I have ruled out my switches.

I have the following repeating
Mar 23 15:12:56 truenas kernel: br-5fa18a95763a: port 1(vethc203870) entered blocking state
Mar 23 15:12:56 truenas kernel: br-5fa18a95763a: port 1(vethc203870) entered forwarding state
Mar 23 15:12:56 truenas kernel: br-5fa18a95763a: port 1(vethc203870) entered disabled state
Mar 23 15:12:56 truenas kernel: eth0: renamed from vethcadeae0
Mar 23 15:12:57 truenas kernel: br-5fa18a95763a: port 1(vethc203870) entered blocking state
Mar 23 15:12:57 truenas kernel: br-5fa18a95763a: port 1(vethc203870) entered forwarding state
Mar 23 15:20:21 truenas kernel: br-d85b1e228c6f: port 1(vethc119b6f) entered blocking state
Mar 23 15:20:21 truenas kernel: br-d85b1e228c6f: port 1(vethc119b6f) entered disabled state
Mar 23 15:20:21 truenas kernel: vethc119b6f: entered allmulticast mode
Mar 23 15:20:21 truenas kernel: vethc119b6f: entered promiscuous mode

there does not seem to be any errors reported on TrueNAS side.

Have you verified your switch? Did you try to reset it when you face problems?