We've recently configured a new Server 2012 with exchange 2013. Everything seems to have gone well.

For some reason, We are unable to connect to the exchange server from a clients PC using the exchange option however, if we choose activeSync then we are able to access the mail. What is the difference between activeSync and Exchange option in outlook and what could be causing the issue?

I've already checked the DNS and the client machine is connected to the domain. The owa can be used successfully on the clients PC. I've tried everything I can think of to debug the issue and I think it will be something stupid that I have forgotten to do to enable this. Has anyone got any suggestions as to what this may be?

I will note however that there is no internet at all and this is just through an internal network that has been configured. So the emails I have tested have been to local email addresses.

Also, the error that I am recieving when I connect from outlook via exchange option is:
The action cannot be completed. The connection to microsoft exchange is unavailable. Outlook must be online or connected to complete this action.

• Edited by LSorsby 18 hours 15 minutes ago Added more information

Hello 

Can you check if port are open on network level using below link.

https://technet.microsoft.com/en-us/library/bb331973(v=exchg.150).aspx

Does the mailbox have any connectivity options turned off? I assume DNS is the Domain controller or a domain controller that is reachable.

Make sure there are no entries in the hosts file that will confuse outlook, c:\windows\system32\etc\hosts

ping of your domain controller and exchange server should work by name and IP address.

Darren

Hi Darren,

As this is a small business The AD DC is the same machine as the Exchange unfortunately. So yes it is reachable. The ping is available on the client machine aswel, as the Autodiscover/Autodiscover.xml. There aren't any hosts in the hosts file as this is a fresh install of the entire system. The only thing I can think that may be causing the issues are either the forwarding as mentioned above or the fact that I'm using a self signed cert.

Have you also tried this user on another PC or another user on this one? it would help to determine if the problem is with the PC or with the server, Mailbox or user.

Autodiscover is "Auto" but yon can still go to accounts and try to manually configure the outlook settings to use exchange, normally we see theses not resolving the exchange server when you try to resolve the name.

you don't have WINS configured or was it ever configured? Client side.

WINS was never configured on this machine as I didn't think it necessary with these PC's being Windows 10. I have just removed the installation and I am currently re-installing the Exchange server so I will try this when the Exchange server has been re-configured as I beleive I didn't install the Filter Packs Prior to the installation. I'm not sure how much difference this would make but it's better to be safe early on in the installation process then hit a problem later on.

I have read of instances where the iis server has been configured to redirect to https. Is this a required process for an internal Exchange Server?

the exchange will listen on https so either going to the https site or putting a  redirect so users that go to http:// will get directed to the exchange OWA properly.

Sounds like you have a bunch going on are you having any authentication issues on this computer too?, maybe the machine needs to be rejoined to the domain or the machine account reset.

No, fortunately the actual to the domain is fine. I've tested it with GPO's and roaming profiles and they all seem to be working as they should be. The only issue really is the Exchange not connecting. Well, The ActiveSync is but the actual exchange connection isn't. When you enter the exchange server address with the username it will not detect the user and comes up with the error:

The action cannot be completed. The connection to microsoft exchange is unavailable. Outlook must be online or connected to complete this action.

Still sounds like the "Exchange Caching" is not resolving to the server how about if you type in the ip address of the exchange server instead of name in proxy does it resolve the ip address to the exchange server name.

Check your connection settings do you have a msstd the same as other working clients

fast and slow network are both on?

and try all authentication options, if these settings are wrong you can change it may work and they will change back after a restart which means your exchange server has a bad autodiscover setting.

Hi,

According to your description, I notice that Exchange server install on server which also is domain controller. It's not recommended, for your reference: https://technet.microsoft.com/en-us/library/ms.exch.setupreadiness.warninginstallexchangerolesondomaincontroller(v=exchg.160).aspx 
For your question, please follow below checklist to complete configure Outlook Anywhere:
1. Ensure all Exchange services running well.
2. Get-OutlookAnywhere | FL to check hostname, authentication, SSL
3. Get-OutlookProvider | FL to check the value of Server and CertPrincipalName.
4. Get-ClientAccessServer | FL Identity,*URI* to check the setting for SCP.

As above mentioned, please enure that all value of outlook client should be match the setting in Exchange server.

Hope it will helpful.