IPhone 5s won't connect to WIFI

Can anyone help?

IPhone 5s won't connect to WIFI. Initially the network kept dropping in and out. Then it requested the WIFI password which I entered but it told me the password was incorrect. This is despite all other devices on the network using the same password. Have hard-reset the IPhone, have reset networks on the IPhone and have re-set the router. All other devices still working on the network using the same password, whereas the IPhone maintains the password is incorrect.

iOS 10.2.1

Please help.