Hi,
Thank you for posting your query.
Kindly follow the steps provided below to resolve your issue.
I would like to confirm the following information with you:
Can we access the file from the problematic client via \IP\files?
When windows firewall was enabled, will all other devices except for the problematic one can access to the file via \servername\fies?
Is there any error message when we cannot access the file via \servername\files? If yes, please provide the screenshot for further troubleshooting.
Meanwhile, please check the Event log via Event Viewer to from both SMB client and SMB server to see if there is any related Event log was triggered when issue occurred, if yes, please provide screenshots of the Event log for further troubleshooting.
Go to this link for your reference and other troubleshooting procedures https://learn.microsoft.com/en-us/answers/questions/368132/unable-to-access-files-on-server-via-unc
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