Hello all, I just found the lifesaver ;-) (for Synology NAS but probalby also useful for others)
I had exactly the same issues with build 2004 and our office Synology NAS ; searching 2 days for a solution...
Make sure you have the latest DSM update installed (important).
Controle Panel
File Services
Advanced
Enable WS-Discovery !!
For those using SMB1 : (I was, due to some former incompatibility issues):
Change to min SMB= SMB1 and max SMB = SMB3 (also under file services)
Reboot NAS
Reboot PC + re-map the NAS network drive
Reboot PC to check if the network drive is still intact and here you go...