I have a program in c# that have connection string for network use to connect to sql server 2008,it works correctly until our company make DC server and join all computers

I change my connection string,then if I log on to my computer(my computer is a server) from any users in DC I can work with program but from other computers I can't

If I change my computer state to work group, last version of program works and I can connect to sql server from other computers in workgroup

Sounds like they've set it up wrong. Not being a system admin, there isn't much else I can add.