Hi,
If you want to enable telnet on the stock R6400 just point your browser to http://<router IP>/debug.htm and select telnet
Telnet to your device and voila. No username and password. Maybe you can enable ssh now for better security.
It will be disabled again after reboot.
Cheers
This doesn't seem to work anymore. The HTML and JS are commented out. I tried to "Edit As HTML" with Chrome, but that didn't seem to work. Anybody have other suggestions?