I have a home network with 5 W10 systems, 3 W8.1 systems and a W7 system. Until a few days ago, all systems could access files on any other available system. Currently, all systems can “see” all other available systems. However, NONE of the 5 W10 systems can access any files on ANY other system. All of the W8.1 systems CAN access files on every other system, including all of the W10 systems. All W10 and W8.1 systems use the same Microsoft login name and password, although 4 of the W10 systems and 1 W8.1 systems are accessed by the same pin. The W7 system can access files on ALL other systems. All systems have a second (local) account, all with the same user name and password. Some of the systems are hard wired, some are wireless. All systems can access the internet.

All of the systems belong to “Workgroup.”

All of the systems show ipv4 connectivity, all of the systems show “No internet Access” for ipv6.

All systems have Network Discovery ON, Auto setup of Network devices ON, File & Print sharing ON, Allow windows to manage Home group ON, Two of W10 machines have 128 bit encryption ON, 2 of 3 W8.1 machines have 128 bit encryption ON. Under “Use 40 or 56 bit encryption”, 3 of 5 W10 machines are ON, 1 of 3 W8.1 machines are ON. 4 of 5 W10’s have “Media Streaming YES, 1 of 3 W8.1’s have it set to YES. All devices with “Media Streaming on” are set to allow.

All systems have “Use Sharing Wizard” selected.

I CAN ping one W10 machine from another W10.

I CAN access media files on other W10 systems through the media player icon in File Explorer Network

All W10 systems are version 10240 RTM

Home group connections appear to mimic the network connections, although I haven’t tested every possible connection as I did with the network interactions.

Using a local login instead of a Microsoft account doesn’t seem to matter.

Security is Windows Defender on all W10, Security Essentials on all others.

[The error is: \\MACHINENAME is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions.

The network address is invalid.

I have tried changing Windows credentials by deleting and reentering MicrosoftAccount:user=, I also added creds for 2 machines in the formTERMSRV/SYSTEMNAME, with MS username, password, but didn't seem to help.

The only commonality I can think of is a bad Windows update. I’ve spent some time researching the problem, but haven’t found any results that correspond to my problem. Any one know of a fix?