Hi @Ian Goo
Does this issue persist all the time?
Does anyone else have the same problem in your organization?
Is your environment online or on-premise?
To troubleshoot your issue, we firstly recommend you try to clear your client cache file by following these steps:
- Log out of Skype for Business/Lync.
- Delete any sign-in info (only in Skype For Business 2013/2016)
- Exit Skype for Business/Lync.
- Navigate to Users > username > AppData > Local > Microsoft > Office > x.0 (x.0 corresponds to the Skype for Business/Lync version: 16.0 = Skype for Business 2016, 15.0 = Skype for Business 2013, 14.0 = Lync 2010) > Lync
- Delete sip_profileName folder.
- Delete all files in Tracing folder. Do not delete the folder itself.
- Clear DNS cache: in Command Prompt run ipconfig /flushdns command.
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