Alibaba Cloud extended the time period during which you can upgrade standard Internet NAT gateways to enhanced Internet NAT gateways free of charge. Starting October 1, 2020, you can upgrade standard Internet NAT gateways to enhanced Internet NAT gateways free of charge. The end time for free upgrades is extended from December 31, 2020 to December 30, 2022.
Features
Enhanced Internet NAT gateways are upgraded from standard Internet NAT gateways and
use a more advanced architecture. Compared with standard Internet NAT gateways, enhanced
Internet NAT gateways provide higher performance and higher elasticity. Enhanced Internet
NAT gateways support flexible billing methods and fine-grained maintenance. For more
information, see What is an Internet NAT gateway?.
Note We recommend that you upgrade standard Internet NAT gateways to enhanced Internet
NAT gateways. This way, you can better manage network traffic that is sent over the
Internet.
Before you start
Before you upgrade a standard Internet NAT gateway to an enhanced Internet NAT gateway,
take note of the descriptions in the following figure. 
For more information, see Upgrade a standard Internet NAT gateway.