In Lollipop, they were exclamation marks. They'd crouch beside your wifi and mobile data icons, and they'd be ugly. But you could remove them....
(1) Open, or install and open, a Terminal emulator.
(2) Type: su
(3) Type: settings put global captive_portal_detection_enabled 0
Well, they're back. And they're a cross.
As of Android 7.1.1, what I like to call Android Nuggets, the captive portal detection (and detection flags) have changed.
Captive portal detection is, um... it's when your phone looks for internet connections that require web logins? A captive portal is a landing page for, like, when you login on a public wifi network. And ffs I don't know but whenever you connect to wifi or data, Android goes looking for Google servers and when it can't find them it says you're not online, and it marks the connection icon with a cross. Also it screws around with whether or not automatic reconnection will take place. If your home wifi is regarded as "Connected, no internet" for instance, your phone won't automatically reconnect next time you toggle your wifi, and you'll have to manually initiate a connection.
In other words, in China, Android will always say you have no internet access even though you're right there surfing your little fingers off.
But, captive portals and this check for connectivity are related... somehow... and screwing with the flags will stop this connectivity check, and coincidentally make a mess of your captive portal detection. (Might want to think about that next time you're in the airport and don't know why you can't find the login page for the free wifi.)
All righty, well here's what you have to do now. (And note: none of this will work if you do not have root access. )
Open a Terminal Emulator. Type in the following commands:
settings put global captive_portal_https_url https://www.google.cn/generate_204
You may have to repeat this procedure for these two as well:
In the real world? The captive portal server in Android 7.1.1 is
What the above terminal commands do is change that server to the only google server accessible in China.