Why can I not map to network drive anymore?

Question

I have two (2) NAS devices I have been using for several years, mapped as Y (SynologyDS420+, 16TB) and Z (WDEX4100, 16TB), connected via ethernet to our network. These are used as RAID backup for working files for our company from desktop USB 8TB and 16TB drives. Backup happens in real time. Right after Christmas, I came into my office and my PC had apparently restarted overnight, I presume due to a Windows Update, despite being set to notify me before installing. Microsoft, right? Anyway, after I logged in, the mapped drives no longer appeared in File Explorer. I attempted to redo the mapping, but I keep getting errors that my domain cannot be found, can't use the credentials, may have already been logged out, etc. Windows 10 Pro for Workstations, Version: 10.0.19045 Build 19045, Dell Precision Mobile Workstation 7750, 64GB RAM. I have tried everything I can find on the internet that addresses this issue, no avail. I have contacted Synology and WD tech support, spent several hours with each troubleshooting, running diagnostics, they report their units are functioning correctly. I can access both units via typing their IP address into browser, can get into admin and verify Shares, users, configuration, etc. On the Synology, I have Active Backup for Office 365 running and it connects with our Office 365 account and still backs up. If I go into Windows Credentials and add credentials manually, I do not get any error message, but nothing shows up in File Explorer like it used to when I would do the same for other devices. In Windows Credentials, both device appear as normal. I have double and triple checked Norton 360 Firewall settings, Network Trust and Device Trust for bot NAS are set to 'Full Trust'. Both devices show up in File Explorer under the 'Network' tab at the bottom, but I cannot access them. Again, these have been functioning wonderfully for several years, until right after Christmas. I am at my wits end and do not have the funds to pay $499 for Windows support on this right now. HELP!

Answer 1

Hi Jerry,

1. Do you have one workstation only or a bigger network managed by Active Directory server?
2. Can reach the NAS devices in Windows File Explorer with UNC path with IP address like: \NAS-IP-HERE\ ? The configured network shares or any error message should be shown. Post it, what happens.
3. Please check, if the current time on your workstation and NAS devices is the same.

Answer 2

Hello and thank you. Yes, we do have a network, it's managed by AD. We run our company using Microsoft 365, have emails assigned through Microsoft 365 Admin Center, manage Teams, SharePoint, etc., through those specific Admin centers. Have been running this way for about 8 (?) years. Have been using NAS devices connected via ethernet using DHCP for about 6 years (a Seagate NAS failed just over 2 years ago and I replaced it with the Synology unit) , this issues began just after Christmas a few weeks ago. I can see the NAS units displayed in Windows File Explorer at the bottom under 'Network', see Capture1.jpg attached. However, I can no longer access them through File Explorer, but typing in the IP address in File Explorer opens a browser and I can access their control panel, verify the Shares, users, settings, etc., as normal. I have had both Synology and WD tech support verify that everything is working, setup as it should be. See Synology.jpg and WDEX4100.jpg Time on my workstation and both NAS units are the same.