I tried a few things like reset network settings or disabling wireless on my iPhone 7 to be only on cellular. It cannot longer sync with my exchange account.
What I did I also upgrade my iPhone 7 and iPad Pro to iOS 10.2. M iPhone 7 and the other iPad still on the previous iOS version are synching fine. It returns the message 'Cannot get mail, the connection to the server failed'. The upgrade went well, but now my email refuse to synch with the server. Yesterday I upgraded my iPad Pro 12.9 to 10.2. I have an iPhone 7, iPad Pro and iPad Pro 12.9. I have an own Exchange 2010 server and all our iOS devices are configured for it.
