Migrating from a Exchange 2013 (only 1 server) to Exchange 2016 (only 1 server) something goes wrong In the intranet all works but when I'm outside my network and i open outlook all works for a few minutes then i can work with only my mailbox. All other mailbox (shared and "full controlled/complete access") are disconnected by themselves

I've used this guide: https://www.kerneldatarecovery.com/blog/step-by-step-guide-for-migrating-exchange-server-2013-to-2016-part-1/

any suggestion?

1 Answer 1


It sounds like your TCP timeouts might be conflicting between your Exchange server and Firewall device. On Windows the default is 2 hours unless you set it in the registry. So the firewall may be cutting off these TCP sessions after a few minutes and the connections get orphaned. Exchange will only allow you to open so many connections and as a result you would lose connections to other mailboxes first.

You should find out what the TCP timeout is on your firewall and then set the value lower on your Exchange server. Go to the following key:


If the "KeepAliveTime" value isn't already there, add it as a new DWORD value. If it is there, edit it. NB This is measured in milliseconds, eg 1800000 (decimal) = 30 minutes.

You will need to reboot the server after setting the value.

Reference - Checklist for Troubleshooting Performance Related issues in Exchange 2013, 2016 and 2019 (on-prem)

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