Mitsubishi Q-Series: Can read data just fine, but cannot write to any points

I have an Ethernet Mitsubishi Q-series PLC. I have configured the device within the TOP Server and when I open the OPC Quick Client I can see the values of Tags. However, I get an error when trying to "write". Event Log is saying that "DIP switch 7 must be switched ON" and the COM Error LED that turns from green to red. There is no DIP switch 7. The PLC processor has only 5 switches and the Ethernet card has none (that I can see).

When I try to write a value to any register, I see the following error within the TOP Server's event log:

Unable to write to '<address>' on device '<device name>.'

There is a setting within the PLC that allows you to control whether or not the device will accept writes to any registers. This setting can be enabled/disabled.

In the PLC Ethernet Configuration, under "Operational Settings", there is an option for "Enable Write at Run time".   Be sure to check this option.

Once the option is set, save the configuration and then download the settings to the PLC.

Upon making this change, all writes should now work okay (assuming the addresses are legal/valid etc.)