Have you tried to create a manual binding for one of the computers (Windows if possible) using the client-identifier instead of the hardware address option?
Router(config)# ip dhcp pool
Router(dhcp-config)# host
[mask | /prefix-length]Router(dhcp-config)# client-identifier
Router(dhcp-config)# client-name
Here is an example (you will need to create one "pool" per computer):
Router(config)# ip dhcp pool PC-1
Router(dhcp-config)# host 192.168.1.5 mask 255.255.255.0
Router(dhcp-config)# client-identifier 01c2.070e.b000.66 --- > please notice that you need to include "01" and change the "." as showed on the example.
Router(dhcp-config)# client-name
Where "c207.0eb0.0000" is the MAC address of the PC.
Microsoft DHCP clients require client identifiers instead of hardware addresses. The client identifier is formed by concatenating the media type and the MAC address. For example, the Microsoft client identifier for Ethernet address b708.1388.f166 is 01b7.0813.88f1.66, where 01 represents the Ethernet media type. For a list of media type codes, refer to the "Address Resolution Protocol Parameters" section of RFC 1700, Assigned Numbers.
To specify the hardware address of a Dynamic Host Configuration Protocol (DHCP) client, use the hardware-address DHCP pool configuration command. It is valid for manual bindings only.
Regards,
Franco
