Test results from speedtest.net and or the app are severly inaccurate on 4G mobile devices. This is a known issue. I recommend using speakeasy.net's speed test. If you want to verify this, upload a large file (at least 1 gig) from your phone to your home PC via FTP and use a stop watch to time it. Of course this isn't perfectly accurate either but is sufficient to illustrate the issues with speedtest.net.