Microsoft has been keeping it off the internet pretty well, I believe there are a couple versions on beta archive and you need special access to obtain it
@tellblom@BenNottelling Sadly we only have server 2016 builds 14282, 14324, 14877 and 14901. They are all “Redstone” builds of 2016, however someone on BA has a copy of “Redstone 3” 2016 16299 however I cannot seem to find that one anywhere on our FTP.
If you’re still interested in these builds let me know!
Sorry to say that I tried these builds around the time the 18* builds of 10 were coming out and none of them booted at all. No errors, nothing. The Pi simply acts as if no sd card is there at all.
I have a feeling they are just too early in the process to do much with, bearing in mind these are ~3-4 years old (early even for the OS itself), but still handy to have them available like this as some day, who knows?