Iphone6 silent mode SMS does not vibrate.

First, select "Sound" in "Settings" and check whether the switch of "Silent Mode Vibration" is turned on.

If it still doesn't vibrate after opening,

Click on the "telephone ringing,

Continue to check whether the "Vibration" option in "Ringtone" is turned on. I set it to "none" before, so there has been no sound. Click the Vibration option.

Just choose a vibration mode when you come in.

What I'm talking about here are all solutions without hardware problems, and some of them are caused by vibrating hardware during sleep. Please see other posts.