trouble shooting rule start from easiest thing .
1- try to check that you are are connected with that server .
2- try to telnet different ports like 53 and others
3- try to do gpupdate on server not working if it gives the same error as RPC is unavailable then try to restart so see the dhcp client and dns services .
4- try to check the DNS records created for all servers .
5- try to restart netlog on , workstation and file replication service .
6- if still doesn’t work try to run netstat and see the port working at back .
7- also check windows firewall .
7- in site and services check that you have you servers as global catalog .
any other help please let me know .