Mail: Cannot connect to server

Hi all,

we got problems while syncing mails between IPhone and Exchange Server.

After setting up an account it always works fine.

But after a few days, the mail app shows an error "Cannot connect to server" and no more mails are synced.

Once appeared, the error is permanent. The following workaround helps immediately to solve the problem:

Changing the timespan of how long mails will be synced. The exact setting is not important, but the change helps.

The problem is user specific, but more than one user is affected.

Only IOS devices are affected. The version of IOS doesn't play any role.

I have downloaded the log file of an affected IPhone, it shows the following:

2016-09-28 12:17:06.722|[227:0x144505130]|LogOther: ERROR: MFMessageErrorDomain/Socket Read - Die Verbindung mit dem Server ist fehlgeschlagen.

I have tried so much to solve the problem. Are there any ideas? Thanks for answering.

Best regards,

Chris