L2TP connection failure guide in VPN

One .windows link 809 error

809 error Or display Unable to establish computer and VPN Network connection between servers , Because the remote server is not responding . This may be because some network device between the computer and the remote server is not connected ( Such as firewalls 、NAT、 Router, etc ) Configured to allow VPN Connect . Contact your administrator or service provider to determine which device might cause this problem .

Method ： reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent /v AssumeUDPEncapsulationContextOnSendRule /t REG_DWORD /d 2 /freg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent /v AssumeUDPEncapsulationContextOnSendRule

Turn off the firewall and before executing windows to update , Right click to open as administrator cmd One input 2 Restart after

Two .windows System 7XX error

Method ： reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\RasMan\Parameters /v ProhibitIpSec /t REG_DWORD /d 1 /freg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\RasMan\Parameters /v ProhibitIpSec

Turn off the firewall and before executing windows to update , Wounding 2 Enter... In sequence cmd in , Restart again

3、 ... and .win10 System L2TP Connection attempt failed

ERROR Because the security layer encountered a processing error while initializing the negotiation with the remote computer  .

Method ： 1 Make sure IPsec Policy Agent Service started

2 Ensure routing and remote access （Routing and Remote Access） And remote access connection manager service （Remote Access Connection Manager） start-up

3 Registry add ProhibitIpSec Registry entries • Registry path HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Rasman\Parameters • establish ProhibitIpSec Registry entries , choice DWORD Type and set it to 1 Value

4 Registry add AllowL2TPWeakCrypto Registry entries • Registry path HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Rasman\Parameters • establish AllowL2TPWeakCrypto Registry entries , choice DWORD Type and set it to 1 Value

perhaps ： 1  Network settings – Change the settings found in the adapter options VPN 2  Right click Properties – Security –VPN Type selection L2TP type , Then select advanced settings and enter the correct shared secret key .