IPhone 6s will say that it did not update because it disconnected from the internet when it never did

IPhone 6s will say that it did not update because it disconnected from the internet when it never did. It will make you enter the unlocking password then it willmke you agree to the agrement .lastly it will say verificating ”something“ not Quite sure what it is and then say it wasn’t possible because it disconected from the WiFi but it never disconnected at any point form the wifi. Please help me figure what the issue is