MAC IN MY NETWORK !! HELP

Hi ..

Our MD have macpro laptop, and he is using at his home wireless network with static ip from another ISP with another DNS, here in the work we are using DHCP, and he saying this must work because every where else works just here not working, why !

To be honest I don`t know how can I figure it out how to make it work, he wanna me make work in both site, work and home without he change anything, and as he said that his mac works normally in the airport, why ??

any idea PLEASE !!!

Thanks in advanced.