Route::resource does not find entity on show action

I am building a ebsite with Laravel 5.5.
I have a resource controller named DouGroupController.

In my routing web.php I tried to do the following:
Route::resource('/dogroups', 'DoGroupController');

When I go to http://localhost:8000/dogroups I get a list of all my dogroups, but when I go to http://localhost:8000/dogroups/1, Laravel can't seem to find my dogroup. I am certain that there is a dogroup with id 1. It also doesn't give an error for id's which do not exist.

When I do Route::get('/dogroups/{dogroup}', 'DoGroupController@show'); it does work.

This is my show function of DoGroupController:

public function show(DoGroup $doGroup)
{
    return view('dogroups.show', ['dogroup' => $doGroup]);
}

and my dogroups.show view, which extends the standard laravel layout which is generated when you run php artisan make:auth

@extends('layouts.app')

@section('content')
    <div class="container">
        <h1></h1>
    </div>
@endsection

Why doesn't Route::resource('/dogroups', 'DoGroupController'); work? And how do i fix it?

via Chebli Mohamed