I thought you had already tried changing cables around? If your router is still sending out a wireless signal whilst also connected via ethernet to another PC there is every possibility that the two will show a different speed. I was under the impression that both PC and laptop were connected by ethernet. You need to switch off the wireless signal and then run the speed tests.
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.