I spent much of Thanksgiving (sadly) testing the WiFi on this phone using WiFi Analyzer and speedtest at locations all over my house. I compared results with an iPhone 3GS Iphone 4 and Samsung Series 6 notebook. The One X (+) was terrible. At times it performed well but in the exact same location, the next time it would perform dismally. Very unpredictable and erratic and I found out why!
** THERE IS A 20+ dbm DROP IN SIGNAL WHEN HOLDING THE PHONE IN THE PALM OF YOUR HAND! **
Now this may be common with a lot of phones, I don't know. But, the signal strength on this phone is already not what I would describe as "Best in Class" so this drop in many areas where the signal is moderately low to very low, holding the phone in the palm usually makes a difference as to if you have a usable connection or not!
I have a highly respected ASUS RT-56U router and made sure I had the latest firmware installed, but as I said, even the iPhone 3GS had more consistent, better, even results compared to this phone in many low signal areas when I held the One X in my hand. So it's not the router, it's the device.
Next step is to try to determine if it is this one phone, the One X+ AT&T model, and the One X AT&T model, or all One X models, including International? I will head to the store to see if they will let me run the test on another phone. I'm praying it is this particular phone but my gut tells me it is probably an issue in the design of the phone. I really like this phone but may have to go for the Samsung Galaxy SIII instead as this wifi issue is BAD, and unacceptable. Would get a Nexus 4 but I need more than 16GB of memory!!!!!
I shot a video about this showing the Wifi Analyzer running:
HTC One X (plus) Weak Wifi Signal Issues - YouTube