Troubleshooting Lync 2010 client connection issues

Please Follow the below-mentioned troubleshooting steps for troubleshooting Lync 2010 sign in issues.

• Download and run the auto fix for Lync 2010 from the Microsoft here
• Restart "Microsoft online sign in assistance service"

To restart the service, you can follow the below-mentioned steps. you can restart the service from the service management console, you can open the same by typing "service.msc" on Start >> Run, or you can restart the service from the Command prompt.

To restart the Service using the command prompt, please open Command Prompt As an Administrator, Once the Command Prompt is opened, then copy & paste the below command on command prompt and hit enter.

NET STOP MSOIDSVC & NET START MSOIDSVC

make sure this command run without showing an error message and says successfully restarted "Microsoft online sign in assistance service"
Once the command completed successfully please restart the Machine.

If the issue still not resolved then reinstall the sign in assistance service.

Uninstalling the Sign-in Assistant

      In Control Panel, under Programs and Features

Select "Microsoft Online Services Sign-in Assistant", and then click to Uninstall/Change.

Once the Service is removed then reinstall the same.

Follow the below steps for installing “Sign-in Assistant Service"

    Download the Sign in Assistance installation package from here    

Once you have the executable downloaded, installed the same, you may be required to run the program as an administrator to install the same, Once the program has installed successfully, please restart the machine and then launch the Lync Program.

I hope this will resolve the issue.

*** If there are still any issues make sure to check the user accounts, sip and email address, also the proxy settings etc from the Server Side.***