TRENDnet TW100-S4W1CA User Manual page 41

The Maximum Idle Time feature can control the connection time (default
time=0, always connect). Check the Connect-on-demand box to enable
your router to connect your ISP whenever an Internet connection is
required.
2-2-5 DNS
The Domain Name System (DNS) is the way that Internet domain names
are translated into Internet Protocol (IP) addresses.
If your ISP provided at least one DNS Server IP Address, type that IP
Address in the Primary DNS address fields. You may also enter another
DNS Server IP Address; the Router will utilize these simultaneously for
quicker access to functioning DNS Servers.