Hi,
My work Exchange Account (Exchange server hosted internally by my IT contractor), linked to my Domain/ ADID keeps getting locked out. Whenever this happens, I have to go to a customized Exchange Online portal and click “forgot your password” and unlock my account.

I have been checking with my in-house IT contractor, but no one knows the problem exactly. I have also searched online extensively. I have read similar problem descriptions and tried the solutions but to no avail.
This is my setup :
I am accessing this Exchange account using
1) Corp issued Laptop (LT). I have to login using my domain\ADID into this LT and then launched Outlook 2016 to access emails.
2) Personal Laptop. Since it is a personal LT, I have subscribed to office 365 and using outlook 365, connected to my office exchange account, login using my domain/ADID. But I login to my personal LT using a generic local username.
3) Iphone default mail application. Similarly, I connect to exchange server and in the configuration setup, I have to specify the domain name , ADID and password.
You may wonder why am I using (2) since I have (1). Due to some corp security concerns, there is no internet access for (1), except for email. Hence, many staff have to work on personal LT as our works require use of internet. (3) is more a convenience for me to access email while on the road.
What I have observed is this. If I assessed email using (1) or (2) or (3) alone, the account is ok.
As long as I use (3) with (1) or (2), that’s when problem begins to appear. As password is kind of “embedded” in iphone email config, it will prompt me to enter password. It seems that whenever I start using (1) or (2), the password will “disappear” in the system and that triggers the system to prompt for password instead. However, 3 strikes and the account will be locked out. I could not even stop that from not happening, it happens automatically, in a way.
As such, I really do not know which system is causing this problem and which configuration in the Exchange server might be causing it. The IT contractor is not willing to look into it as (2) and (3) are devices which they do not support. They are not incorrect as the system works well if we use (1) solely.
Some threads suggested it may be new IOS issue but this happened only to Exchange server account. My gmail setup in iphone default mail app do not have such problem. Hence, I could not check in IOS thread.
Do you have any idea what could be the issue ? Thank you.
