Win 10 file sharing problem

Just an update on the latest state.
Only one PC is now giving problems. It's also the oldest one. It uses a TP Link Wi-Fi dongle, on the 'main' Wi-Fi circuit. It has multiple boot - Win
10, Win7 and XP all on individual HDs. Win 10 on a new SSD. Booting Win7, it works fine with everything.
Win 10, it can see and share with the laptops, but not the other way round.
Both laptops show it in nework. One appears to access it, but shows only Disk F. Which doesn't exist. And if you open it shows empty.
Other one says something like 'you haven't got permission to access this computer - see your network administrator' or whatever.
And since I've got 4 computers I've recently updated to Win10, they're all set up in the same way. Turning off the Windows Firewall makes no difference.
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*WHAT IF THERE WERE NO HYPOTHETICAL QUESTIONS?

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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A mixture. The one giving problems a clean install on a new SSD.

Yup - that's all very similar to Win7.
--
*A clear conscience is the sign of a fuzzy memory.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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