OnePlus has now started rolling out Open Beta 14 for OnePlus 3 and Open Beta 5 for OnePlus 3T users. Both the beta updates are exactly the same in terms of features along with an identical changelog. This new update is based on Android 7.1.1 Nougat.
OnePlus 3/3T users who are already running preview Open Beta (13 and 4), should be automatically notified of these new updates. The OTA update weighs in at 1388MB.
If you’ve already flashed a previous Open Beta build, you will receive this update via OTA. If you haven’t, you will need to flash this build by ADB sideload. You can grab the files of Open beta 5 and 14 for the OnePlus 3 and 3T from the below link.