Use production Application Gateway SKU#
Application Gateway should use a minimum instance size of Medium.
An Application Gateway is offered in different versions v1 and v2. When deploying an Application Gateway v1, three different instance sizes are available: Small, Medium and Large.
Application Gateway v2, Standard_v2 and WAF_v2 SKUs don't offer different instance sizes.
Application Gateways using v1 SKUs should be deployed with an instance size of Medium or Large. Small instance sizes are intended for development and testing scenarios.