Would you suggest holding the home power button or just shutting down and putting it back on?I'll provide a slightly more constructive answer. If you are having issues go into the settings and turn it off then back on. Then reset the device. Do this for both devices. Report back with any issues.
for my ipad air and iphone 6 works only for calls(receiving and calling)
safari or mail doesn't work and both are using the same icloud account and wifi
What did you do specifically? Just shut off facetime and put it back on?It worked for me after fiddling with the Facetime and Apple ID settings.