I install OS X Server for MDM profile manager on iMac with High Sierra. Then used Apple Configurator 2.5 to enroll 16 iPad Air 2 on iOS11 to the MDM and added wifi Profile. All iPads are showing up as supervised devices on AC2. Now on each iPad, I see the Remote Management screen, hit the NEXT on the top right corner to attempt to install the remote management, and they all came back saying failed timed out. The same profile worked fine on iMac.
This might be the reason, look at Apple's compatibility list of devices for Apple Configurator 2 -- iPad Air 2 is not listed.