Internet Connection Sharing Windows 2000

I have 2 PCs running Windows 2000 Professional. The 1st one is connected to the internet by dial up modem. The 2 PCs are networked.

The 1st PC is supposed to act as an Internet server but for some reason DHCP has stopped working and I can’t access the internet from the 2nd PC client.

I can access resources on the server by using static IP addressing on the client PC instead on using DHCP.

How do I make the server PC start working as a DHCP Server again?

I hope someone can tell me the answer to this please?