Step 3. Perform scoping and isolation: Log in to O365 Portal to verify if Password is correct Specific user or whole organization is affected? Try on different machines Try different network MFA Enabled? Check if SFB (in OWA) can be loaded
Step 4. If issue is machine specific, do the following: delete credentials from Credential Manager Remove the certificate from the certificate store (certmgr.msc) delete the sip profile folders in “%localappdata%\Microsoft\Office\16.0\Lync” and delete the contents of Tracing folder.
Step 5. Use manual configuration (to see if the client is having issue retrieving information from the internet) Skype for Business Client > Options > Personal > Advanced > Manual Configuration Type in “sipfed.online.lync.com:443” on both Internal and External Server
Step 6. Obtain and check the ff. logs Get the UccApi logs and review for any errors. Get Fiddler logs to check for responses from network devices like (ex. Firewall, Proxy Server, etc).