Hi Peter,

I used this solution below and my MBP back to login in my Lync server:

Microsoft Lync is the new rich client for Lync users on the Mac platform and offers integrated functionality for instant messaging, presence, conferencing and voice. Lync for Mac is designed to work with both Lync Server 2010 and Lync Online to help you: Control communication costs; Improve user productivity; Gain operational efficiencies. Step 2: Click Download to load Lync for Mac 2011 setup file with dmg file format. Step 3: Open dowloaded file and setup Lync for Mac. Fix Skype for Mac OS X 10.5, 10.6, 10.7 - Duration: 6:23.

Before you install the Lync for Mac 2011 14.0.9 update, you must uninstall any version of Lync for Mac 2011 that is earlier than Lync for Mac 2011 14.0.4 from your computer. Additionally, make sure that the computer is running Mac OS X 10.5 or a later version of the Mac OS X operating system. My company uses Microsoft Lync for IM, presence, soft phone, etc. Most of the company runs it on Windows, but I had to be different and use a Mac. After installing the Lion update that was rolled out today, 10.7.2, the recently released Microsoft Lync for Mac 2011 client would not work, it simply crashed at login. The only skype 4 biz client for Mac is Lync 2011 right now. There is something in preview and also something for iphone and ipad, but not OSX. Our sales guys need to be able to meet and call external clients. Am I missing something? It seems weird that the Windows client can do this, but the Mac OS X client cannot.

This Fixed My issue, I make sure you always allow the trust in the last step.

To resolve the 'Sign in to Microsoft Lync failed because the service is not available or you may not be connected to the Internet.' you need to reimport your Lync server certificate.

Ask your system administrator of the Lync server to export the server certificate and provide to you:

- Log into Lync server

- Open MMC > Add/Remove Snap-in > Select Certificates > Click Add > Select Computer account > Click Next > Local computer > Finish > OK

- Expand Certificates > Personal > Certificates

- Click on the certificate with the fully qualified domain name (i.e. Lyncserver.xyz.com) with the intended purpose 'Server Authentication'

- Right click > All Tasks > Export > Next > No, do not export the private key > Select Base-64 encoded X.509 (.CER) > Next > Give it a name (fully qualified domain name) > Next > Finish

Once provided with the .cer file, exit Lync on your Mac, double click the .cer file to import it into your keychain. Once imported, double click the certificate in Keychain and in the Trust section change 'When using this certificate' to 'Always Trust'.

Start Lync back up, and you should be able to log in.

Lync 2011 For Mac Os Catalina

Oct 7, 2016 1:05 PM