Why am I unable to associate an EIP with a NAT Gateway in the NAT Gateway console?

If you have created a NAT bandwidth package for a NAT Gateway before 23:59 January 26, 2018, you still need to use the bandwidth package to associate public IP addresses with the NAT Gateway. To associate an EIP with a NAT Gateway, choose one of the following operations based on the billing method of the NAT bandwidth package.
  • If the NAT bandwidth package is billed by fixed bandwidth, follow these steps:
    1. Log on to the VPC console.
    2. In the left-side navigation pane, click Quota Management.
    3. On the Quota Management page, click the NAT Gateway tab, and then apply for the bandwidth package allows covert to common package privilege.

      The system automatically approves the application after 10 seconds.

    4. Call the ConvertBandwidthPackage action to convert the NAT bandwidth package to an Internet Shared Bandwidth instance. For more information, see ConvertBandwidthPackage.
    5. On the Quota Management page in the VPC console, apply for the nat console allows bind EIP privilege.

      The system automatically approves the application after 10 seconds.

    6. Sign out and then log on to the VPC console. You can view the associated EIP on the NAT Gateways page.
  • If your NAT bandwidth package is billed by traffic, open a ticket to apply for whitelist authorization and then repeat the preceding steps.

Can I create an SNAT IP address pool for an EIP?

Yes. You can create an SNAT IP address pool by calling API actions. For more information, see Create a SNAT IP address pool.

How many EIPs can I associate with a NAT Gateway?

Item Limit Quota increase supported?
The number of EIPs that can be associated with a NAT Gateway 20 Yes. For more information, see Manage quotas.
The number of pay-by-traffic EIPs that can be associated with a NAT Gateway 10 Yes. For more information, see Manage quotas.

Why am I unable to reach peak bandwidth after I associate an EIP with a NAT Gateway?

The number of EIPs associated with a NAT Gateway limits the Max Connections of the NAT Gateway. The Max Connections of a NAT Gateway associated with only one EIP is 55,000. If the bandwidth at which the ECS instances access the same public IP address and port is greater than 2 Gbit/s, packets may be discarded due to limited ports. To resolve this issue, we recommend that you associate four to eight EIPs with the NAT Gateway and create an SNAT pool.