Skype for Business is an excellent collaboration tool.
After all, time is money.
There might be an issue with the Domain Name System configuration for your domain.
Try adding the correct DNS entries, and save the changes.
you’ve got the option to then give a shot to sign on again.
For more information, seeTroubleshooting Skype for Business Online DNS configuration issues in Office 365.
It seems that antivirus programs and VPNs sometimes interfere with the Skype for Business login process.
It appears this is because Skype for Business already encrypts your data, and login conflicts may potentially occur.
Use theRemote Connectivity Testto assess your remote connectivity to Skype for Business servers.
