Hello and welcome,
this route is not valid:
<td><%= link "link", to: Routes.product_path(@conn, :create, product) %>
You may want to link product’s show and edit pages, there:
<td>
<%= link "show", to: Routes.product_path(@conn, :show, product) %>
<%= link "edit", to: Routes.product_path(@conn, :edit, product) %>
</td>
:create route is used to post a new product, instead. You can see its usage in templates/product/new.html.eex, when it is assigned as the :action of the rendered form.
