Creating a Virtual Network gateway in an Azure environment is not a rocket science. But there a few things that you need to clearly defined and if you missed them, then, will kill your day to find solutions for those errors.
To configure the Virtual network gateway select the “Virtual Network Gateway” by going into the ore services as shown below.
If you see your Virtual network in inactive that means you have to create the Gateway subnet for this network.To do that you can go into Vnet > Subnet then you can go into “Gateway Subnet”
But If you have deployed by using the default configuration then you will not be able to
add the CIDR (Classless Inter-Domain Routing). That is because you cant use a overlapping IP range.
To overcome this you can change the “Address Space”. Here I have change to *.*.*.*/16 Which will be easy for me to manage my demo environment. but when you are doing this, you should plan this properly to reduce the unwanted broadcasts.
Once that is done, You can assign a name for the Gateway and a Static IP for the Gateway.
Hope this helps you to configure your Virtual Gateway in your Azure environment.