Draytek Vigor2500V Manual page 56

NAT
The MultiNAT can be deployed where your ISP offers you multiple public IP
addresses by your ISP. As a result, you can have a one-to-one relationship
between a public address and a private IP address. This means that you
still have the security from NAT but the computer or laptop can be addressed
directly from the outside world by its associated public IP address, but still by
only opening specific ports to it (e.g. TCP port 80 for an http/web server).
To achieve it, you should find the path to click the button of WAN IP Alias
which is located inside Internet Access Setup.
You follow the path Internet Access>>MPoA if your ISP offer you with MPoA:
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