These are some of my troubleshooting notes to fixing the cannot connect to UNCs (Windows cannot access) or map to network shares error. Try one thing at a time, test a UNC, try the next step.
Verify on Client Machine
Enable – Turn on sharing and connect to devices
Start – Workstation service
Install – File and Print Sharing for Microsoft Networks
Install – Client for Microsoft Networks
Check – File and Print Sharing Not blocked in firewall
Enable SMB1 – Control Panel > Programs and Features > Enable SMB 1.0: check SMB 1.0/CIF; uncheck Automatic Removal
Start – Computer Browser service
Enable – NetBIOS over TCP/IP
Start – Netlogon service (if on a domain)
Reg Keys
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
dword: LocalAccountTokenFilterPolicy
value: 1
HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\
dword: EnableLinkedConnections
value: 1
HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters
dword: RequireSecureNegotiate
value: 0
HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation
—delete DependOnService & DependOnGroup
HKLM\SYSTEM\CurrentControlSet\Services\Mup\Parameters
dword: EnableDfsLoopbackTargets
value: 1
HKLM\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
dword: Smb1
value: 1
HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters
dword: Smb2
value: 1
HKLM\SYSTEM\CurrentControlSet\Control\NetworkProvider\Order
string: ProviderOrder
value: RDPNP,LanmanWorkstation,webclient
Commands
netsh winsock reset all
nbtstat -RR
net view \\%computername%
sc.exe config lanmanworkstation depend= bowser/mrxsmb10/nsi
sc.exe config mrxsmb20 start= disabled
net use x:\\IP_ADDRESS\ShareName /user:username password