crwdns2934241:0crwdne2934241:0 rokin154

crwdns2934249:0crwdne2934249:0:

iOS 11 works well on my 6s so I don't think the model itself  has a problem.  I have noticed a couple of glitches on my iPad 4.

I'd try to do a factory reset and see if you have the problem without any of your stuff on the phone.  If all's well then try to do a restore from backup.

crwdns2915684:0crwdne2915684:0:

open