MS Entra ID/Azure MFA issues Sept 9th?

At around 3 PM yesterday (UK time) we began noticing that none of our staff were able to login to our Horizon VDI environment externally. After entering credentials in the Horizon Client it would hang at “Authenticating” before displaying “Internal server error” normally at this point they would get prompted for MFA.

Our external UAG uses Radius Auth which goes to an NPS server with the Azure MFA extension installed.

Nothing was being logged on the NPS or Azure MFA extension side as though the traffic was going nowhere. We tried rebooting NPS along with the UAG and even tried removing and reconfiguring the MFA extension but with no luck.

Eventually at around 6PM MFA prompts were suddenly working again.

Did anyone notice issues yesterday?