How do you know you upgraded a wrong firmware ? Where did you get the firmware ? Have you set your wireless adapter a static IP first ? On their website, you can download the quick installation...

Have you set your wireless adapter a static IP first ? On their website, you can download the quick installation guide: http://www.tp-link.com/en/products/details/?categoryid=&model=TL-WPS510U#down

"I tred to change the IP address to 192.168.2.100 (so that there is the same gateway as the router). After reboot screen of the AP I am not able to connect anymore to the AP new IP address...

1, Make your laptop can print when it is straightaway connected to your printer firstly; 2, Do not change the printer properties on your computer; 3, Reinstall the TP-link USB printer controller. Can...

It seems that you have a lot of client devices, including TV and game console. Hohoho, they are all high-bandwidth consumption devices. Maybe the WR841ND is not so stronger to handle them all...

here is a helpful link http://www.tp-link.com/en/article/?id=400