Apple has released the fourth beta version of iOS 11.2 beta for developers(Read what's new here). tvOS 11.2 beta and watchOS 4.2 beta are also available for testing, this firmware is available in 3uTools, you can download and upgrade now.
Which devices are compatible with iOS 11.2 beta 4?
iPhone 8, iPhone 8 Plus, iPhone 7, iPhone 7 Plus, iPhone 6s, iPhone 6s Plus, iPhone 6, iPhone 6 Plus, iPhone SE, iPhone 5s; 12.9-inch iPad Pro 2nd generation, 12.9-inch iPad Pro 1st generation, 10.5-inch iPad Pro, 9.7-inch iPad Pro; iPad Air 2, iPad Air, iPad 5th generation; iPad mini 4, iPad mini 3, iPad mini 2; iPod touch 6th generation.
Step1: Connect your iDevice with USB cable to your PC and then launch the latest version of 3uTools.
Step2: Go to "Flash & JB" -> "Easy Flash", select the firmware iOS 11.2 beta 4. And then click "Flash". (If you want to save iDevice’s data, please select the checkbox "Retain User's Data While Flashing".)
Step3: 3uTools will automatically flash your iDevice, please wait patiently for around 5 to 10 minutes till the process finishes.
iDevice will restart automatically after this process, then you can activate iDevice by manually or activate iDevice with 3uTools.