IPSEC VPN Troubleshooting

Considering that Internet connection exists and it is functional or it was in the near past: end user can/could browse the internet
Component Failure Diagnostic Possible causes To Fix
BackOffice Systems No PC/ Location can connect Corporate systems malfunction Routers/Servers configuration (IT)
Lost corporate internet connection Corporate IT contacts provider
INTERNET at large One or more locations can not connect, while some can
Connection interrupted randomly		 Massive traffic, DOS (Denial of service attack) ongoing on some core network Try any of the following:
  • Use alternate method (e.g. Citrix)
  • Connect from a different location if possible
  • Wait for improved conditions
Access provider Browser internet access works fine,
VPN can neverconnect		 Provider blocks IPsec, or certain ports (e.g. UDP 500, etc.) Any of the following:
  • Use alternate method (home, hotel connections)
  • Change provider if possible (home)
Most probable (at least 90%): End Point connection
Access point (cable/dsl modem and router) Browser internet access works fine,
VPN canneverconnect		 Hardware/Software does not support VPN (see Access provider above) Any of the following:
  • Use alternate method
  • Contact Internet Service provider for access point configuration.
  • Replace hardware with VPN compatible - where possible.
Wired connection No internet access at all, previously Browser and VPN worked

PC unplugged (power saving disconnects network card)
Cable not connected
Cable damaged
Wireless active (routing conflict)
  • Plug PC to A/C adapter and plug the adapter to the A/C wall outlet.
  • Verify proper cable connection.
  • Replace the cable.
  • Disable PC wireless card.
Wireless connection Only browser or no internet access at all, previously Browser and VPN worked Poor signal
Connected to the wrong access point (AP)		 Use cable connection
Change location
Verify / connect to the properAP
PC also connected on cable (routing conflict) Disconnect cable
Browsing works fine, No VPN at all Wireless AP does not support VPN Use alternate method
Change wireless AP
Contact ISP for configuration
VPN connection works intermittently, connection drops at random, even when active.
Browsing works, possibly slow at times.		 Poor signal Change location
Use alternate method
Use cable connection
Radio interference
Other wireless devices (PC, Access Points, game console, wireless handsets)		 Use cable connection
Try alternate method
Try to change location (unreliable)
Try different radio channels (time consuming, often unreliable)
Radio interference:
power lines, Electrical equipment, fluorescent lighting, wireless handsets		 Use cable connection
Try alternate method
Try to change location (unreliable)
User’s PC Browser works, VPN doesn’t work from any or certain locations, other PCs work Software corruption:
VPN client, Windows, undesirable new software/malware, S/W Firewall inadvertently enabled/ misconfigured		 Reinstall/Update VPN client,
Virus/malware scan
Further professional troubleshooting in the IT lab
Re-image PC if the case
End User All systems in good working order, VPN worked, not anymore End user forgot procedure/password Refresh user training, verify/update passwords
VPN connection drops after 5 - 15 minutes Inactivity timeout Reconnect VPN
Connect VPN only when needed, do required work and disconnect.