Can’t join the domain a member server

Dear Colleagues,

I’m trying to join a Windows Server 2003 SP2 R2 computer as a MEMBER SERVER to an existing Windows Server 2003 SP2 domain.
But unfortunately I was not able to do that due to error that permanently occurred: “The specified network path is no longer available”.
1. Could you guide me or share the link where all the issues have been discussed, please?
2. If anyone is aware of a such error, could you tell me the solution, please?
3. Is it necessary to extend schema to be able to join the domain R2 servers as a member server?

Thank you all in advance.