you need to setup you router, that is the issue.
Complete the following steps to see you right:
Open up a web browser and access the 205 control
panel, generally located on
http://192.168.1.1 and/or
http://voyager.home
Select the 'Advanced' option on the left of the screen
to open up the advanced configuration page and then
click the 'Advanced....' option.
Enter your username and password when prompted, the
default username is 'admin' and the default password
is also 'admin'.
Select the 'IP Routing' option in the menu on the left
and then choose 'NAT Virtual Server/DMZ' from the NAT
Options.
Left click on the 'Add' button and then select 'DMZ'
from the rule flavour menu.
Enter a number not previously used by another rule
into the 'Rule ID' box, '60' should be fine for most
people.
In the 'LAN IP Address' enter the IP address of your
XBOX, provided you have left the XBOX at defaults then
the first IP not managed by the DHCP server is
'192.168.1.35' and this will suffice.
Left click on the 'Apply' button and then left click
on the red 'Save' button on the left.
You should then get a confirmation window which you
can just close.
Thats the Voyager 205 configured for you, just need to
set up the XBOX now:
Make sure that there is no cd/dvd in the XBOX and then
connect it to the 205 using an ethernet cable.
Start up the XBOX and then select 'Settings' from the
main menu.
Choose the 'Network Settings' option followed by 'IP
Addresses'.
Change the Configuration option to 'Manual' and then
enter the following settings into their respective
slots:
IP ADDRESS: 192.168.1.35
SUBNET MASK: 255.255.255.0
GATEWAY: 192.168.1.1
Go back to the 'Network Settings' menu and choose 'DNS
SERVERS'.
Again set the Configuration to 'Manual' and enter the
following:
PRIMARY DNS: 192.168.1.1
SECONDARY DNS: 192.168.1.2
Finally just go back to the 'Network Settings' screen
and press connect.
Ok that should be it.
Alfie