All Outlook clients failing to connect to Exchange 2016

Thomas Grassi
Thomas Grassi used Ask the Experts™
Exchange 2016 CU9 DAG 2 Nodes
Windows 2016 Data Center
Outlook 2013/2016

Today I woke up and all my Outlook clients are disconnected from my Exchange 2016 Servers.

Restarting the clients did not help

starting outlook in safe mode did not help either

I can access the accounts via OWA

Hope I can resolve this before everyone gets in today

What can I look for?

Any commands?

Thank you in advance
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I guess you already checked database mount status.
Have checked whether you have any DNS issue?
Also outlook connectivity?
EE Solution Guide - Technical Dept Head
Most Valuable Expert 2017
Things to check
1. Ping which is configured in your Mapi virtual directory.
2. Ensure database is mounted
3. open outlook with /RPCDIAG switch and see what is the error.
4. Make sure you can reach server.
5. Finally Please recycle the mapi application pools or iisreset
6. If there is any change in app pools please revert back and recycle.

Hope it helps.
Thomas GrassiSystems Administrator



Thank you for your help

reverted back app pool change restarted IIS  now clients accessing
Thomas GrassiSystems Administrator


REopen this

Clients not connecting again

Exchange 2016 is crap

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