I have seen others having ethernet speed issue with other vendor's routers using the 2012 Mini. Google it. I assume you have checked the preferences/network/ethernet/advanced/hardware settings. Try...

May not be the issue but something to check. Make sure you click "save" after making changes. Sometimes you need to scroll down the page to see the save button. I like to power cycle the router after...

TP-Link AX6000 or wait for the AX11000. Also be sure your ISP speed is high enough to support all those devices. Also your modem could be the limiting factor. How fast is it and how many up and down...

Any time you have speed issues, bypass the router and connect direct to the modem via ethernet cable and do your speed checks. More often than not, it is the ISP. You can also try power cycle the...

Are you connecting via WIFI? if so, be sure your wifi ssid is unique. On your device, delete (forget) the wifi network and reestablish the network.

If you can sign on to the router, you can see the MAC address in the advance settings.