Hello, Zarathustraa,
First, I'm going to give you a possible solution to your issue, have you checked your input method for your keyboard press 'Windows Key+ Spacebar' to change it, sometimes if you login as a different user it will change the keyboard input method. Eg, US-Keyboard or United-Kingdom-Keyboard, I just thought I would say this it's caught me out a few times.
Now, I'm not advising you on how to hack a router, and I won't. I'm advising, you to not ask 'how to hack a router', on one of the major producers of 'top end routers' in the world. The simple fact is routers are made to be un-hackable, but you and I know nothing is un-hackable. I have been in your situation, you forgot to back up the settings on your router after making major changes to the setting which improved the lag on your favorite game.
My last bit of advice is 'dude', DON'T HACK YOUR ROUTER, take it on the chin. Learn from the mistake, and never repeat it again. I have been there! Reset the router and go through and set it up again, with all the best setting like you did before.
By the way, if you do try and succeed in hacking your router, the manufacturer will come down on 'you and your system' like a tone of bricks! You will end up in court and will end up with a lot of debt.
Good luck, Zarathustraa, and stay safe!