On 24th March Apple released a new iOS 8.4.3 (12H885) for Apple TV 3 update fixing the option to jailbreak the device. Software Update 7.5 is available for AppleTV3,2 (released in 2013, A1469 for Rev A) and AppleTV3,1 (released in 2012, A1427). Learn how to downgrade Apple TV 3 to iOS 8.4.3 (12H876).
Apple TV Software Update 7.5 includes general performance and stability improvements and one new feature. Control your Apple TV from Control Center: You can now control your Apple TV (3rd generation) from Control Center on all of your iOS and iPadOS devices. If you can live without this feature and like to install PlexConnect on your jailed device install the older firmware.
Downgrade Apple TV 3
To jailbreak Apple TV 3 with iOS 8 it's required to use iOS 8.4.3 (12H876) for Apple TV 3 released on 24th September 2019. You can easily downgrade iOS 8.4.3 (12H885) to the supported version using a Computer or Mac and iTunes. The firmware is still signed and there are no issues with downgrading.
Step 1. Plug your ATV into your MAC via USB (for ATV3 you will need also use the power lead).
Step 2. ATV will appear in iTunes or Finder app asking if you want to restore to factory settings.
Step 3. When you see the box saying download and install, hold down the option key first.
Step 4. Select the previously downloaded iOS 8.4.3 (12H876) firmware.
Step 5. The firmware downgrade should only take about 5 mins to complete.
Step 6. In the end, it will say your box can be unplugged.
Step 7. Plug back into your TV, run the setup program.