Draytek Address Mapping changed following firmware update
It's sometimes necessary to set a server to have a particular outgoing IP address on broadband setups that have multiple IPs.
Draytek have been changing their menu structures for popular routers such as the Vigor 2820 and Vigor 2830 series. These changes are quite confusing and documentation may not match the version you are using.
Settings for mapping a particular internal (LAN) IP address to a particular external (WAN) IP address may be found in one of three different places, depending on the firmware version:
1) Older Firmware (eg 2820 220.127.116.11_2471201) had a menu item "Address Mapping" under the NAT menu.
2) Later Firmware (eg 2830 18.104.22.168_sb_232201 had a menu item "Policy Route" under the LAN menu.
3) In later Firmware still (eg 2830 22.214.171.124) these address mappings are done under the "Load-Balance" menu.
The above may apply to other similar Draytek routers such as the Vigor 2850. There also may be other variants of the menu structure affecting address mapping in addition to the three detailed above.
It would be good if Draytek kept consistent terminology and explained these changes in their FAQ.
As taken from http://www.chilternbusinesscomputing.co.uk/news/draytek-address-mapping-changed.htm