Win10 can't connect to Win8.1 but Win8.1 can connect to Win10

Sorry for the delay in responding... I'm swamped recovering from this year's Texas storms (both inside and outside)

From my going through the clues the AllowInsecureGuestAuth parameter seems to be there in order to prevent enterprise users from going to guest shares because of the potential of infecting a company network and it makes sense in that environment, but not in a private lan where you need access between computers on your own lan.

With that in mind, I looked at the same registry entry on the computer that COULD access the computer that could not access other shares and found that the AllowInsecureGuestAuth parameter was not in that computer's registry entry.  SO, I went back to the other computer, removed the parameter, rebooted, and still was able to access the computer that had not been reachable when the parameter was present and set to "0"

That would tend to indicate that an update or other action had added that parameter and created the problem over a year ago.

fwiw, here are some url's that helped me get to this point;

https://www.kapilarya.com/fix-you-cant-access-this-shared-folder-because-your-organizations-security-policies-block-unauthenticated-guest-access

This one contains a screenshot of the helpful "group policy" dialog that came up when I used the "RUN \<computername>" https://docs.microsoft.com/en-us/answers/questions/59309/you-cant-access-this-shared-folder-because-your-or.html https://www.youtube.com/watch?v=vyatMj1Z2NQ https://docs.microsoft.com/en-US/troubleshoot/windows-server/networking/guest-access-in-smb2-is-disabled-by-default

I sincerely hope this issue is resolved.

Thoughts and comments solicited,

Beverly Howard

That setting is frowned upon in here...

https://docs.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/microsoft-windows-workstationservice-allowinsecureguestauth

AllowInsecureGuestAuth

But I can't say I fully understand what that article is talking about.

SUCCESS! I finally found the answer to this problem!

I'll post additional information and links when I have time... probably in the next day or so.

The problem is that a "group policy" was set to default to NOT ALLOW CONNECTIONS TO "GUEST" shares. Not sure why, but it looks like this is inconsistent on different installs... perhaps something related to the OEM machine that didn't matter earlier, but got "turned on" probably with updates when this happened over a year ago.

The network connection restriction can be dealt with in a registry entry.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters

The parameter AllowInsecureGuestAuth set this to 1 If the parameter does not exist, add it (watch case) and set it to 1

The file explorer error messages were of zero help, then, today, on a hunch, I entered the name of the computer (\<computername>)using RUN and got a different dialog.

Searching for the text in that dialog found a discussion and a youtube video that showed the above registry entry.

Hope this helps others... it's a shame that other discussions on this problem have been locked and cannot be used to notify those who participated in them.

Beverly Howard

I wish stairs weren't involved, but exercise, after all, is good. But I'm sorry I couldn't help more.

>> Win 10 can see the Win 8.1 computer in the Network folder, & its shared files are accessible.  <<

The Win10 can't even "see" the Win8.1 computer when it can't transfer files

>> Nothing needs to have been done on the Win 10 side.  <<

When I'm sitting at the Win10 computer and need to sync files to assure that I am not going to create a conflict and doing so requires descending two flights of stairs to get to the Win8.1 computer and then climbing back up those stairs to work on the Win10 computer ...its a problem.

>> It's not that tough a workaround. <<

From my viewpoint, when you are pushing 80, having to take a round trip down and then back up up two flights of stairs every time this happens qualifies as "tough" ;-)

Beverly