User`s manual

Transmission Mode
The default method of selecting the transmission mode for RJ-45 port is
10/100 Mbps and for RJ-11 port is 5/15/25Mbps. Therefore, if the link signal
is disrupted (e.g., by unplugging the network cable and plugging it back in
again, or by resetting the power), the port will try to establish communications
with the attached device via auto-negotiation. If auto-negotiation fails, then
communications are set to half duplex by default. Based on this type of
industry-standard connection policy, if users are using a full-duplex device
that does not support auto-negotiation, communications can be easily lost
whenever the attached device is reset or experiences a power fluctuation.
The best way to resolve this problem is to upgrade these devices to a version
that support Ethernet and VDSL.
Physical Configuration
If problems occur after altering the network configuration, restore the original
connections, and try to track the problem down by implementing the new
changes, one step at a time. Ensure that cable distances and other physical
aspects of the installation do not exceed recommendations.
System Integrity
As a last resort verify the switch integrity with a power-on reset. Turn the
power to the switch off and then on several times. If the problem still persists
and users have completed all the preceding diagnoses, then contact an
authorized dealer.
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