>I'm guessing it's a local server problem.
No, I don't think so. When builds 25272 and 25276 were originally released I run update to four devices at same time and only one of those had this long delay. Besides those two release days I have try that same update many times from different starting builds and it's always same points where that long delay happen.
As told in blog it's known issue and MS is working on it.
- [NEW]Β Some users are experiencing longer than expected update times installing recent builds. We are actively investigating this issue.