Windows network issue - Not all computers can connect to server after router swap

Small office network. Router had to be replaced There is a Windows 7 machine used as a server, and a handful of Windows 10 machines used by staff. The Server's drives are shared and an MS Access database is run from it. Following the router swap, all Windows 10 machines show the server in the network list, but only half of the computers are able to open the shared drives and connect to the database.

When trying to open the Server from Network in Windows Explorer for those that do not work, the following are the errors:

Windows cannot access \Server1 (longer description saying that there may be error in spelling or issue with network). Error code 0x80070035 The network path was not found.

"Diagnose" results in : Your Computer appears to be correctly configured but the device or resource (Server1) is not responding.

Clearly, I have inadequate networking knowledge to resolve this. I find the inconsistent connectivity from various computers to be challenging for troubleshooting.

Any help appreciated!

Fix error 0x80070035:

1. Check TCP/IP NetBIOS Helper service.
2. Enable NetBIOS.
3. Disable third-party firewall.
4. Reset the Windows 10 Update components.
5. Run SFC scan.
6. Run the Update Troubleshooter.
7. Whitelist the Windows Update servers.
8. Run DISM.

Hope this helps.

Regards, Jerry.