Exchange 2013 - Outlook Credentials

[KarlGoddard]

Morning all

 

I've got a bit of a head scratcher...

 

We have an on prem Exchange 2013 server. As of mid last week any external Outlook connection fails and the end user just repeatedly gets a credentials login box when opening Outlook. Internal clients work fine, just external clients using Outlook on any OS - Win10 / Win 11 / Mac fail.

 

OWA works fine, putting a staff device that doesn't work externally onto the internal network works fine..

 

I've spoken to our NM and he's not pushed out any updates to the Exchange box, or any config changes to our Smoothwall...

 

Totally puzzled. Any pointers as to where I should look next?

[psydii]

https://techcommunity.microsoft.com/t5/exchange-team-blog/released-march-2023-exchange-server-security-updates/ba-p/3764224

 

https://learn.microsoft.com/en-us/microsoft-365/enterprise/exchange-2013-end-of-support?view=o365-worldwide

 

(I'm still running a 2013 box, sorting that out is pretty close to the top of my to do list, but I long ago turned off remote access to the server, all the users are connecting to Exchange Online / Microsoft 365)