Hi @Quentin Roberts ,
When I move a mailbox from the Exchange 2010 server to the Exchange 2016 server I am unable to connect to ActiveSync as I normally would.
Is there any detailed error message when this occurs? Are you able to connect normally if reconfiguring the decive(Although noramally this is not necessary as I know.)?
Any clues if performing an Exchange ActiveSync test using Microsoft Remote Connectivity Analyzer?
In case it is due to the delay after moving the mailbox, please try to manually recycle the following two applications pools in IIS on Exchange 2016 server and see if it works:
- MSExchangeAutodiscoverAppPool
- MSExchangeSyncAppPool
Furthermore, after Exchange 2016 was introduced into the environment, have you completed the post-installation configurations like updating the autodiscover SCP, configuring the URLs for Exchange 2016 virtual directories, updating the DNS records to point to Exchange 2016 server and so on? For more details, you may generate a checklist using the official tool Exchange Deployment Assistant or refer to the guidance in the links below:
EXCHANGE 2010 TO EXCHANGE 2016 MIGRATION – PART 3
EXCHANGE 2010 TO EXCHANGE 2016 MIGRATION – PART 4
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Addtionally, if you have any anti-virus software or firewall configured in the environment, it's suggested to try temporarily disabling it to help troubleshoot the issue. As based on my research, similar issues could be related to the NAT policy that still pointing to Exchange 2010, see:
Activesync Authentication Fails after Mailbox Move
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