A few days ago, Microsoft removed all the ISOs from the Windows Insider Website. The move signaled that the company was obviously getting ready to upload new ISO files, and today that moment has finally arrived. There are now new Redstone 5 ISO files for build 17713, along with the older ISO files for Redstone 4 builds 17127, and 17115.
As usual, these can be found from the Advanced Preview Download section of the Windows Insider website. They also all come in three flavors--- Insider Preview, Insider Preview Enterprise, and Insider Preview Home China.
Build 17713 was released about a month ago and came with the usual set of fixes and known issues. It was also recently added to the Slow Ring and introduced new features like web sign-in to Windows 10, and some inking and Notepad updates.
Despite promises from Microsoft, there has been a major lack of Slow Ring Redstone 5 builds, so this is likely why we're only seeing one new ISO added to the Insider website today. It's also strange to see the company still offering Redstone 4 ISOs as these have long expired and would no longer activate. Anyway, development of Redstone 5 is nearly done, and as more Slow Ring builds release, we'll likely see more ISO files soon. Keep those fingers crossed!