Are the IP currently manually assigned or using DHCP? If using DHCP when you reboot the device it should request a address upon startup and if you have correctly change the VLAN and its within a new DHCP scope then it should be getting a new address.
Likewise if you have changed the VLAN the camera is on and its now on a different subnet then technically it shouldn;t be communcating with the dashboard as its IP address won't be correct for that subnet.
I suspect you have miss configured your VLAN settings somewhere.
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