Lost net connection

[76nemo76]

Hi All,
      I have a freebsd 12 machine connected to a network switch.
The network switch is sometime switched off and on again
(but not the FreeBSD machine)  and
then the network is lost on the freebsd machine.

I have tried a lot of commands (ifconfig for instance) to restart the network
without any success. Only a reboot makes the network working again.

I should mention that the machine has 4 ethernet ports
used in a bridge (all the ethernet ports are in the bridge)

Do you have any idea?

Thanks
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