I am now waiting on my second replacement 16 MB Nexus 4 to arrive. The first two had an issue that appears to be a hardware problem. When you blanked the screen when connected via WiFi, about a minute later the phone would turn WiFi off. This, in spite of having the "Keep Wi-Fi on during sleep" set to "Always" in the advanced WiFi settings. You notice this WiFi sleeping behavior because running apps like Gmail and Facebook no longer receive notifications of new mail and messages. When you turn the screen back on you can watch the WiFi signal icon which is now greyed out turn blue as it reconnects.
More important for me is that GrooveIP, my must-have voip phone app, no longer answers calls when the screen is blanked. A phone that doesn't answer calls, while maybe attractive in concept, is not of much use.
I bought the unlocked Nexus so that I could drop my expensive Verizon plan and sign up for a less-expensive data-only plan from T-Mobile. I tried out GrooveIP on my Nexus 7 for a while and found it to be a completely acceptable alternative to a traditional cell phone. The dialer interface feels just like a regular smart phone, and GrooveIP interfaces with your Google contacts making it a nice integrated component of the Google infrastructure. GrooveIP works well over both WiFi, and 3G and 4G mobile carrier network connections.
Interestingly, it is only the WiFi connection that sleeps when the screen is blanked. When connected to T-Mobile, the phone works as expected.
When I first encountered this issue I thought it was a bug in GrooveIP, and so I contacted the developer of the app. It turns out that he has Nexus 4 as well. We checked and he is running the same 4.2.1 Android rev. as my phone, but it did not have the same WiFi problem. This leads me to suspect that there is a hardware issue with at least some of the LG Nexus 4s.
In addition, there is a known bug in bluetooth in 4.2.1 that effects the Nexus 4. That issue is described in the previous post in this blog.
The good news, I guess, that that Google has a surprisingly efficient device support team, at least so far as their being able to ship me a couple of replacement phones. I'm interested to see if the next replacement has the same issue. My Nexus 7 which is also running 4.2.1, btw, does not have this particular problem.