HTC Calendar 1 hour off - Exchange 2013

[AC Question]

I have a user with an HTC One connecting to our Exchange 2013 for mail, contacts, calendar. All of the sudden, many of his appointments are 1 hour slow. A 2pm appointment shows as 1pm. This only seems to be an issue for recurring appoints, i think.

I have deleted the account and re-added. I have cleared cache/data on the device. I have deleted partnership in OWA. I have configured manual time zones and 2nd time zones to be local to our EST. Nothing seems to fix.

If I connect any other phone, such as my Galaxy s5, no issues and the calendar is correct. OWA and Outlook are correct too. This seems isolated to this HTC device.

Latest android 6.x OS. Verizon.

 

[Rukbat]

Only two things come to mind:

1) His phone time is set wrong (it should be set to automatic, and he should be getting the correct time from the tower).

2) Some setting in Exchange (there are too many things you can do with Exchange to guess) is incorrect, but it's only showing up in his account.