You have to make sure you're set up to use NAT (network address translation). Your internet provider will only allow one IP address to appear on their network at a time.
Your router has to be set up also for DHCP and it will automatically hand out IP addresses to the devices in your home, but will only present itself as a single IP address to the DSL modem.
The base station/router documentation should have some diagrams and settings for you to follow.
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