I'm running into a strange issue for the past couple of months. Whenever I'm on 3G and going to various sites, I'm getting 503 errors intermittently. It doesn't matter what the site (or content) is, but it would just spit back an error. To be more clear, only the web browsers report a 503 error. Reloading once or twice helps to clear the error. Every other app reports it as an unknown or unexpected error. This problem goes away if I switch to WiFi. What could be the cause of this issue? Are my APNs not configured correctly? edit: I should also say that I have a Nexus 4.