similar problem since 11.0.0 until now with 11.1.2
screen freezes to touch, but still moves if something is moving on screen - homebutton still works.
Also much weaker wlan signal, sometimes no gps
resetting didn't help, or just for a couple of hours. Same with fixing the ios with reiboot
What helped with the freezing i: use the powerbutton to get in the lock screen, unlock it and see if it moves again, sometimes it needs a couple of tries.
Then doubletap the homebutton and kill every open app if the display is responsive.
After that it works including gps until there are a lot of apps open again
Didn't figured out how to help with the weak wlan, maybe this has been a sideeffect to the "krack" fix