Tried a different XP computer, same deal.
It can connect to everything - except for HP.

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Reinstalled Windows (10, 1803, 17134.407) for the umpteenth time!
Early on prompt (during the initial setup) asked me about sharing, I said yes.
After that, did nothing more but change the Computer Name & Workgroup (to the same Workgroup as all the rest of the computers).

Created a directory, C:\TMP.
Right-click, Share with (or some such), Everyone & set Full access.

\\localhost shows that it is shared.


Once again, XP can see HP, but when I try to actually access it, "\\HP is not accessible...".


A different Win10 was also able to see HP, but too was unable to actually access the share until I added a Password to my HP User Account. That done, I copied a file from different Win10 to HP.

But XP to HP is still FAIL.

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Install Windows (10, 1809, 17763.168).

No change.


(Win10 takes forever to install. Win7, I can install in a flash. 10 took hours.)


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Just some stuff to look through in the morn...

https://www.google.com/search?q=network+sharing+windows+10+home+and+xp&btnG=Search&gbv=1
https://support.microsoft.com/en-us/help/318030/you-cannot-access-shared-files-and-folders-or-browse-computers-in-the
https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/connecting-pcs-and-users-for-sharing/fb92e439-5dbc-4367-9857-1ef360e9ffdf
https://helpdeskgeek.com/windows-xp-tips/share-files-between-windows-xp-and-windows-7-8-10/
https://www.tenforums.com/network-sharing/2129-sharing-files-windows-10-windows-xp.html