outlook 2011 does’nt connect to Exchange 2010 WiFi

hello,

I have several MacBook (Pro / Air) in a Windows environment.

The mail server is Exchange 2010.

MacBook experiencing some difficulty connecting to the Exchange server while others do not experience problems.

They are all in Yosemite and Office 2011 is updated.

In any case, Outlook is able to connect to Exchange if the MacBook is connected wired.

However, some MacBook are unable to connect to Exchange if they are connected to WiFi.

The Exchange server is local.

I can not find information that talks about this problem.

All suggestions are welcome.

Thank you!