It's a conflict of slugs.
You will get conflicts if you have the same slug for a page and a CPT that uses that too. So for you, your CPT is using 'product
', and your page is too. That's conflicting and causing the 404.
Rename your page Product Info
page' slug to product-info
.
For safety purposes flush your permalink cache by setting them to Default, saving, then saving them as what you had previously.