This just started for me. I'm getting 12 down on a gig speed. Wifi is fine. No changed made to the PC. Something is up and it just happened recently.
moved from my account app area to home network area
Have you tried using a different port on the gateway device ? How about a different ethernet cable ?
Also, have you tried power-cycling / re-starting the device ? No joy ? Try hard resetting the device to factory defaults by pressing and holding in the recessed reset button on the rear for 30 seconds. This can sometimes clear up some weird behavior issues. You will lose any customized settings, and they will need to be re-configured from scratch if you do the latter.