Lync 2010 mobile can’t connect to the server. it may be busy or temporarily unavailable

Dears, I would like to share the following article with you,

In the last week we have renewed the Lync 2010 internal and external certificates, internal and external desktop client working normally without any issue, but the mobile client can’t connect.

General Info.

Mobile application requests for Mobility Service.

mobile application requests for Mobility Service

PS Both the internal Mobility Service URL and the external Mobility Service URL are associated with the external Web Services FQDN. Therefore, regardless of whether a mobile device is internal or external to the network, the device always connects to the Microsoft Lync Server 2010 Mobility Service externally through the reverse proxy.

Issue symptoms

Lync Mobile users get the following Error message “can’t connect to the server. It may be busy or temporarily unavailable” while trying to connect.


Investigation result

· After reviewed the mobile client logs and simulate the test by the test Lync connectivity analyzer, I have found that An error occurred while mobile client sending the request to the Lync proxy server even through port 443 or 80.

. In my scenario we don’t have a reverse proxy, instead of that we using the Lync Frontend servers as a proxy server at the same time, it has a two IPS on the same NIC,22 for internal services and,51 for the proxy server.

PS. This is not supported scenario, you must use a separate server for the Revproxy if you are going to use software like TMG or any other else, and that if you don’t have a reverse proxy device.

. We use the HW load balance for High availability for the internal and proxy services.


In my case the IIS web service component of the internal and external sites was missing the binding configuration, so that if you have the same case with the same scenario all you want to do is assign the proxy IP to the external site with port 443 and public cert, and assign the internal server IP to the internal site with port 443 and internal cert.


One thought on “Lync 2010 mobile can’t connect to the server. it may be busy or temporarily unavailable

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.