Your IT department can best answer that
If they can't help (perhaps you are a one man operation) you might try the tech support of your VPN software provider.
Another tip for troubleshooting VPN connections....
If you use a router try by passing it as a troubleshooting step. Most routers must be setup to support VPN connections and some old ones do not support all types of VPNs. ("login" errors can be caused by routers that do not support the VPN protocol your software uses for login to a vpn server.)
Ferengi Rules of Acquistion:
Rule # 47 Don't trust a man wearing a better suit than your own.