Unable to access files on server via UNC

-Adam 1

Hello all!

I've been trying unsuccessfully to access the files of a server (running WS2019 non-GUI) on our LAN via UNC path. I have been able to access the files of other servers on the LAN, but not this one.

While troubleshooting, I disabled Windows firewall on the target server, and was then able to access that server's files! So, it's obviously a Windows Firewall issue. From what I've read, port 445 needs to be open, but it already is. Is there another port I should be looking at?

All servers on the LAN are in the same workgroup; this is not a domain environment.

Thanks,
-Adam

2 answers

Sunny Qi 10,906 Reputation points Microsoft Vendor

2021-04-23T06:30:08.367+00:00
Hi，

Thanks for posting in Q&A platform.

Before we go further, 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.

Best Regards,
Sunny

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-Adam 1 Reputation point

2021-04-23T16:03:33.23+00:00

Thanks for the reply!

No. Using the IP address doesn't work either.

I'm not sure I understand the question. Other servers on the LAN can access files from each other using \server\c$. However, they cannot access files from the new/problematic server nor can the new/problematic server access files from other servers.

Yes, there is an error message (see attachment).

I'd say SMB log info is probably not related.

SMB Server > Operational last log was 4/14 ("The file and printer sharing firewall ports are currently closed. This is the default configuration for a system that is not sharing content or is on a Public network.").

SMB Client > Connectivity last log was also 4/14 ("Event 30810 - A TCP/IP binding was added to the specified network adapter for the SMB client.")

Thanks, again, for your help!

Sunny Qi 10,906 Reputation points Microsoft Vendor

2021-04-26T05:59:35.827+00:00

Hi,

Thank you so much for your feedback.

While troubleshooting, I disabled Windows firewall on the target server, and was then able to access that server's files!

May I know if the target server means SMB server or SMB client? If it the SMB server, please make sure the port 445 and 139 were open.

You could check whether these ports were opened by running command telnet 127.0.0.1 445 and telnet 127.0.0.1 139 separately in a cmd window with admin privilege from SMB server side.

Best Regards,
Sunny

-Adam 1 Reputation point

2021-04-26T13:20:45.48+00:00

Hello Sunny,

Sorry - I don't know about SMB server vs SMB client. What can I look at to help get you that answer? As a reminder, the target server is the non-GUI version of Server 2019.

Prior to my previous response, I did add Windows Firewall rules explicitly opening ports 445 and 135-139 for all profiles on the target server (the server I'm trying to access). But, that doesn't seem to have made any difference.

When trying the suggested commands with admin privilege (from cmd or powershell) I get a message stating 'telnet' is not recognized.

I don't know why I'm having so much trouble with accessing another server on the LAN. I've never had this issue in the past.

Thanks, again, for your help!

Sunny Qi 10,906 Reputation points Microsoft Vendor

2021-04-27T09:09:50.197+00:00

Hi,

Thanks for your update.

Regarding of SMB client and SMB server, if you access the shared folder on server 2019 from a windows 10 device, then windows 10 client is the SMB client and server 2019 is the SMB server. In your scenario, I think the target server is the SMB server. The other servers which we initiated connect to the target server is SMB client.

Regarding of telnet command, we should enable telnet client in Windows Server 2019, for more detailed steps, please refer to this article:

How To Enable Telnet Client in Windows Server 2019
Please Note: Since the websites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.

Best Regards,
Sunny

-Adam 1 Reputation point

2021-04-27T11:50:49.903+00:00

Thanks, Sunny.

While this was evidently a firewall issue, I didn't know which rule (it seems firewall defaults on WS2019 are different than earlier versions?). The rule causing this issue turned out to be in the "Network Discovery" group. Still not sure exactly which one, yet as I've enabled the whole group. I'll have to whittle it down to a specific rule when I have time.

Thanks, again, for your willingness to help and for the information you've provided!

-Adam

Sunny Qi 10,906 Reputation points Microsoft Vendor

2021-05-07T04:17:05.873+00:00

Hi Adam,

Thank you very much for your update and sorry for my late reply since I was out of office from 4/29 to 5/5.

You could check if the following rules related 445 was enabled in Firewall of problematic server:

File Server Remote Management (SMB-In)

File and Printer Sharing (SMB-In)

Best Regards,
Sunny
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Tanmay Jog 1 Reputation point

2022-02-04T20:48:07.917+00:00

Are you sharing the folder which you are trying to access remotely? Right-click on the folder you wish to access and from properties, share the folder first
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