0Windows shares not connected after wake fixed

I’ve had a very long stand­ing prob­lem where mapped drives on Win­dows PCs are shown as dis­con­nec­ted after a PC wakes from sleep or after a reboot. Click­ing to open the drive res­ults in a delay of sev­er­al seconds and then the share opens. I had this prob­lem with Win­dows 7 right through to Win­dows 10 1909. Today, thanks to a dif­fer­ent issue, I finally cracked it.

The prob­lem is caused by Microsoft’s out-dated Net­BIOS name res­ol­u­tion sys­tem. I (like most people) map drives to the name of the tar­get serv­er, and with “short­names” (i.e. names without a domain after them) it seems like Win­dows tries to resolve the name with some­thing oth­er than DNS.

I dis­covered that dis­abling Net­BIOS manu­ally (see how below) meant that net­work drives were con­nec­ted cor­rectly after a reboot. I real­ised that if I could dis­able Net­BIOS via DHCP i could fix all the PCs on my net­work with very little trouble. I tested this (instruc­tions below) and was again successful!

Manually disabling

• right click on the net­work­ing icon in the sys­tem tray
• “Open Net­work & Inter­net Settings”
• “Change Adapter Options”
• Right click on the rel­ev­ant con­nec­tion and select properties
• Double click on “Inter­net Pro­tocol ver­sion 4 (TCP/IPv4)”
• Click on “Advanced…”
• Click on the “WINS” tab
• Untick “Enable LMHOSTS Look-up”
• Select the radio box for “Dis­able Net­BIOS over TCP/IP”
• Reboot

Disabling via DHCP

• This will depend on your DHCP sys­tem — mine is a pfsense router
• In the DHCP Options set option 43
• On my pfsense box this is set to a string with a value of 01:04:00:00:00:02
• On a son­icwall box I found the type was set to “byte­value” and I had to use a slightly dif­fer­ent format which was 0x01;0x04;0x00;0x00;0x00;0x02
• In both instances we are effect­ively set­ting the same value which I believe is a hex. Notice that both have 6 “bits” with the val­ues 1,4,0,0,0,2. For dif­fer­ent sys­tems I found a quick google will provide the appro­pri­ate format
• Delete the pre­vi­ous IP lease on the DHCP sys­tem, and then do an “ipcon­fig /release” “ipcon­fig /renew” (2 sep­ar­ate com­mands) on the client