Can't access domain shared folder by name but I can by ip

Can't access domain shared folder by name but I can by ip

I have server with windows server 2008 r2, router works as dhcp, after I
created domain on it, and created users, making clients access the network
via new users of domain then the computers work fine but after sometime
some of them cant access folder of domain server except by using it's ip,
sometime when I change the ip of the client then it's working fine but
after a while the problem comes again. appreciate your help.