One of the first things I noticed when I started using my new router, was that I could not log in to the device’s web interface using Chrome as a browser. Like many other routers (I’ve had at least two, including a Linksys one), my new Draytek doesn’t really use the username field, and the manual advices to leave it empty. But it seems that’s exactly why Chrome is having trouble. When I tried ‘admin’ instead, I was able to log in.
So, if you’re having trouble logging in to configure your router, try using a generic name like ‘admin’, ‘user’ or ‘root’, or see if the manual lists a default username. Not because your router needs you to enter it, but because leaving the username field empty seems to upset Chrome. This issue probably isn’t exclusive to routers, but most other services will require a username anyway.