I know what IPv4 and IPv6 are. For various reasons, relating to multiple email accounts and so on, we choose to run a small mail server on my desktop, which my wife's laptop uses for POP and SMTP. We have a BT Home Hub router.
Lately she's found that her laptop will sometimes fail to pick up mail, so I investigated. I tried pinging the desktop (by local network name) and found that the laptop was resolving an IPv6 address to do so (but then timing out). So I wondered if something somewhere was getting muddled and whether restricting the communication to a single protocol would work better.
I tried disabling IPv6 on the router (not easy, limited settings available, but I did disable address allocation, which should do it, and then renew the leases). No change. Then l disabled IPv6 on the laptop. That forced it to use IPv4, and it resolved the desktop's IPv4 correctly, but still timed out.
Next to the desktop. Like the laptop originally, that had addresses in both spaces. So I disabled IPv6 there too. Hey presto, pinging from the laptop got a pong, so to speak, and the email check from the laptop also worked (as you might expect).
I do realise that an IPv6 device can't talk to an IPv4 one without a gateway to translate, but here both machines had both types of address. I'm a bit on the edge of my knowledge. Are there known issues with Windows 10 PCs getting muddled when talking to each other with both protocols available? As above, this is an intermittent issue, not a systematic one.
And for that matter, given a network that also has Android and Apple mobile devices, a not-very-smart TV with a Roku stick, and sundry other stuff, is it better just to stick with IPv4 on the LAN?