xamarin Unable to resolve dependencies

widows 8.1, vs2017

tied to fallow the "hello world" tutorial...

After creating the project - tried to update all packages on Nuget - and i got this error with 10 more warnings..

Severity Code Description Project File Line Suppression State
Error Unable to resolve dependencies. 'Xamarin.Android.Support.Design 25.4.0.1' is not compatible with 'Xamarin.Forms 2.3.4.267 constraint: Xamarin.Android.Support.Design (= 23.3.0)'. 0

i have tried to use the repair option of the vs installer, and tried to reinstall xamarin...

but i keep on getting same issue.

regards