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Ethernet Error (TCPP0027): The default gateway ... of the device ... is not in its subnet.

For the device mentioned in the error message, a gateway address is specified which is outside the addressed subnet specified by the entered subnet mask.

The subnet mask describes IP networks and specifies how many bits at the beginning of an IP address are interpreted as net prefix. It separates each IP address into a network prefix used for the network identification and a device part for the device identification. This way, the subnet mask determines which IP addresses a communicating device with a specific IP address has to search in its own network and which addresses are located in other networks.

The network prefix must be identical for all devices within the same network (subnet) and the device part must be different for unique device identification within a subnet.

Remedy

  1. Double-click the error message to directly jump to the wrong gateway address.
  2. Enter a gateway address that matches the specified subnet mask.