Bridging an Interface do not deactivate DHCP Server on this Interface
If you setup a DHCP server on an aktive interface and after this you bridge that device with another one, the dhcp server settings are still active for the webinterface.
you can not deactivate the dhcp server on a bridge interface because you can not select it, you also can not set dhcp relay service, because of active dhcp server settings.
deselect/deactivate services if a interface swapped to bridge mode and told this to the administrator.
do not block services with not active but selected services.