On my iPhone I have something called Wifi Assist:
With iOS 9 and later, you can use Wi-Fi Assist to automatically switch to cellular when you have poor a Wi-Fi connection.
What is the first Android version that supports this natively?
What is the earliest version that suppprts iPhone Wifi Assist equivalent for Android?
Question
Answer
So apparently Google implemented it in 2014 in Android, and you couldn't properly disable it. Not even today.
I believe this feature is baked into Android.
Windows 8.1 definitely had it in 2014 according to this https://support.microsoft.com/en-us/help/10652/windows-phone-cellular-and-sim-settings I'm pretty sure Windows Phones predating this also had it although documentation seems lacking.
Wi-fi assist was introduced in iOS 9(2015). https://support.apple.com/en-us/HT205296
There are apps for Android that do this but at least this one is 3rd party. No sources says it predates 2015. I have not experimented enough with this on Android. https://www.guidingtech.com/54831/get-ios-like-wi-fi-assist-android-using-speedify/
Q & A
How to resume reading document opened in google pdf viewer
Xperia Z2 D6502 can't reboot into recovery
Why does Android show more space used in internal storage than what adds up in the details?
Install multiple apps from Play Store with single click
Should I format /sdcard and /data if I want to wipe all personal data with Cyanogenmod?
What happens to my Google Play Music library when I unsubscribe?
Getting absolute path with "ls" command
What is this lock screen with ads and how do I remove it?
Nexus 6P wrong time
xPosed Installer on HTC One M8
SSHFS from Android to NAS
How to make Google Play services and other default white-listed system apps Doze?
Is it possible to get the password from a wps wifi connection?
LG4 - Can't Find App's Data
"Too many attempts. Please try later." message on first Dropbox login after install
Bricked Nexus 7 in Recovery Mode
What do the terms root, bootloader unlock, custom recovery and ROM installation mean?
System apps location on Android Jelly Bean
Nexus 4 disable vibrate
Google Play Games doesn't restore highscores?
Xperia Z2 D6502 can't reboot into recovery
Why does Android show more space used in internal storage than what adds up in the details?
Install multiple apps from Play Store with single click
Should I format /sdcard and /data if I want to wipe all personal data with Cyanogenmod?
What happens to my Google Play Music library when I unsubscribe?
Getting absolute path with "ls" command
What is this lock screen with ads and how do I remove it?
Nexus 6P wrong time
xPosed Installer on HTC One M8
SSHFS from Android to NAS
How to make Google Play services and other default white-listed system apps Doze?
Is it possible to get the password from a wps wifi connection?
LG4 - Can't Find App's Data
"Too many attempts. Please try later." message on first Dropbox login after install
Bricked Nexus 7 in Recovery Mode
What do the terms root, bootloader unlock, custom recovery and ROM installation mean?
System apps location on Android Jelly Bean
Nexus 4 disable vibrate
Google Play Games doesn't restore highscores?
Topics
2D Engines 3D Engines 9-Patch Action Bars Activities ADB Advertisements Analytics Animations ANR AOP API APK APT Architecture Audio Autocomplete Background Processing Backward Compatibility Badges Bar Codes Benchmarking Bitmaps Bluetooth Blur Effects Bread Crumbs BRMS Browser Extensions Build Systems Bundles Buttons Caching Camera Canvas Cards Carousels Changelog Checkboxes Cloud Storages Color Analysis Color Pickers Colors Comet/Push Compass Sensors Conferences Content Providers Continuous Integration Crash Reports Credit Cards Credits CSV Curl/Flip Data Binding Data Generators Data Structures Database Database Browsers Date & Debugging Decompilers Deep Links Dependency Injections Design Design Patterns Dex Dialogs Distributed Computing Distribution Platforms Download Managers Drawables Emoji Emulators EPUB Equalizers & Event Buses Exception Handling Face Recognition Feedback & File System File/Directory Fingerprint Floating Action Fonts Forms Fragments FRP FSM Functional Programming Gamepads Games Geocaching Gestures GIF Glow Pad Gradle Plugins Graphics Grid Views Highlighting HTML HTTP Mocking Icons IDE IDE Plugins Image Croppers Image Loaders Image Pickers Image Processing Image Views Instrumentation Intents Job Schedulers JSON Keyboard Kotlin Layouts Library Demos List View List Views Localization Location Lock Patterns Logcat Logging Mails Maps Markdown Mathematics Maven Plugins MBaaS Media Menus Messaging MIME Mobile Web Native Image Navigation NDK Networking NFC NoSQL Number Pickers OAuth Object Mocking OCR Engines OpenGL ORM Other Pickers Parallax List Parcelables Particle Systems Password Inputs PDF Permissions Physics Engines Platforms Plugin Frameworks Preferences Progress Indicators ProGuard Properties Protocol Buffer Pull To Purchases Push/Pull QR Codes Quick Return Radio Buttons Range Bars Ratings Recycler Views Resources REST Ripple Effects RSS Screenshots Scripting Scroll Views SDK Search Inputs Security Sensors Services Showcase Views Signatures Sliding Panels Snackbars SOAP Social Networks Spannable Spinners Splash Screens SSH Static Analysis Status Bars Styling SVG System Tags Task Managers TDD & Template Engines Testing Testing Tools Text Formatting Text Views Text Watchers Text-to Toasts Toolkits For Tools Tooltips Trainings TV Twitter Updaters USB User Stories Utils Validation Video View Adapters View Pagers Views Watch Face Wearable Data Wearables Weather Web Tools Web Views WebRTC WebSockets Wheel Widgets Wi-Fi Widgets Windows Wizards XML XMPP YAML ZIP Codes