I have a model Vigor2600 annexA, firmware 2.5.6UK. My ISP gives me a static IP address so I'm trying to run a laptop as a home server. In the vigor administration page I managed to setup port forwarding (in NAT Setup -> Configure port redirection table) so that port 22 if forwarded to the private IP 192.168.1.12. Now I can ssh into my laptop from outside, using the static IP from my ISP.

But the problem is that the private IP address 192.168.1.12 is assigned to my server by the Vigor when the server connects via DHCP, and the vigor does not always assign this IP address, sometimes the server connects and gets 192.168.1.13, or something else, and then I need to change my port forwarding rule.

I can't find anywhere in the Vigor's administration pages to say 'always assign the IP address 192.168.1.12 to this machine (identified by its mac address, probably)'. Is there a way to do this? Or do I need to configure my server to connect with a static IP instead of by DHCP?

Thanks