DoorBird D21 Série Manuel D'installation page 14

Any defects caused by direct sunlight are not covered by warranty.
The network cable between the device and the PoE-Switch/PoE-Injector/Inter-
net Router can have a maximum length of 80 meters/262 feet (IEEE 802.3).
If you have only two wires available at the assembly location, you
may use of the "DoorBird 2-Wire Ethernet PoE Converter A1071",
sold separately. It allows you to transfer network data (Ethernet) and
power (PoE) with a simple two-wire cable over long distances. For
example; existing buildings with a simple two-wire bell wire can be
equipped with network technology without having to retrofit any
network cables.
STEP 4: REMOVING THE FRONT PLATE
Remove the front plate carefully using the screw driver provided with the
device from the mounting housing (backbox).
1.) Turn out the
security screws for
1 cm
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2.) Pull down the
front panel.
3.) Pull the front panel
towards you.