Yeah, it can be done. On the WAN configuration page of the router , please go to Advanced setup (by clicking the Advance button on the bottom), and then you can choose to use your own DNS server.

It seems like a DNS proxy failure , you can try to use a different DNS server like 8.8.8.8

http://www.tp-link.com/en/support/download/?model=TL-WA850RE&version=V1#tbl_j On their website, it says you can modify the repeated SSID , on the newer firmware.

You can go to control panel and find firmware remove option, you can find the configuration utility there. You can turn to google for help , if you have trouble doing that

What a weird problem, have you tried different slot and reinstall the driver?

Have you tried using different wireless security type? Just mess around withe the wireless settings and wireless security settings, sometimes It helps .