.. and please don't say it can with the hidden WDS function. I've tried. Though it saves the WDS mac address in the field, the option to enable it disappears after a reboot.

But, yes. Hard reset the router with it plugged in. Make sure you are not running any other DHCP servers on your network, then connect the cable to a LAN port.
If that fails, well, the other thing to try is setting your computers IP manually.