@Neo007 

It's hard to tell what has happend after firmware update.

Usually these things go smooth, if you don't interrupt the power supply during the procedure.

There's two cases:

1.You still have access to the router's WebGUI - login and double check your wireless settings.

2.You don't have access to the router's WebGUI.

In both cases if it still doesn't work as expected, reset the router to its factory defaults and re-configure from scratch.

To hard reset, power on the router and press and hold the reset button with a paperclip for 10 seconds or until the lights flash, then wait for it to reboot to its default settings.