I'm have an issuing when copying a file from a Windows 10 workstation to a FQDN Windows server 2003 resource.

The environment is as follows;

Windows 2003 SP2 Server (x86) (Domain Controller)
FQDN = server1.company.local
IP Address =
NETBIOS NAME = server1

Windows 10 Pro workstation (x64)

The issue manifests in both a command line and windows file explorer environment.
Here is a command line example using robocopy (the issue also happens with copy/xcopy)

TEST1 (NETBIOS) robocopy c:\test \\server1\data\temp file.dat = file copies OK
TEST2 (IP ADRESS) robocopy c:\test \\\data\temp file.dat = file copies OK
TEST3 (FQDN) robocopy c:\test \\server1.company.local\data\temp file.dat = file copy is very slow / unsuccessful

server1.company.local resolves to the correct ip of

This issue only manifests on the two Windows 10 systems we have in the business. We have 70+ WIndows 7 systems that do not present the issue.
The issue temporarily resolves when the effect Windows10 system is rebooted but the issue re-manifests hours/days later.

Thanks in advance . . .