I have an USB dongle from Planet. Model name is WNL-U554

It's listed as wlan1 = 8171 Realtek Semiconductor Corp. RTL8188SU 802.11n WLAN Adapter

It does detect access points but it can't connect to them, I'm just trying to access an AP, not monitoring or anything. Out of sheer luck I once managed to connect to my home router, I could telnet to the router settings, haven't managed to do that again.

What could be going wrong?