Install a tvOS profile to stop your device from downloading software updates — useful for staying on a jailbreakable firmware.
How to verify: after installing, go to Settings → General → Software Update. If it says "iOS is up to date", updates are successfully blocked.
Open this profile link in Safari on your device
Tap "Allow" if prompted
Go to Settings → General → Profile (may be called Profile & Device Management or VPN & Device Management)
Tap the tvOS Beta Profile, then tap "Install" three times (enter your passcode when asked)
Restart your device when prompted
⚠ Removing the profile may let your device update to a higher firmware you can't jailbreak.
Go to Settings → General → Profile (may be called Profile & Device Management or VPN & Device Management)
Tap the tvOS Beta Profile
Tap "Remove Downloaded Profile"
See Jailbreak Checker to find which firmwares are jailbreakable.