Help Center/ Virtual Private Network/ FAQs/ FAQs - S2C Classic VPN/ General Questions/ What Can I Do If VPN Connection Setup Fails?
Updated on 2024-12-04 GMT+08:00
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What Can I Do If VPN Connection Setup Fails?

  1. Check the IKE and IPsec policies to see whether the negotiation modes and encryption algorithms at both ends of the VPN connection are the same.
    1. If the IKE policy has been set up during phase one and the IPsec policy has not been enabled in phase two, the IPsec policies at both ends of the VPN connection may be inconsistent.
    2. If you use a Cisco physical device in your on-premises data center, it is recommended that you use MD5, and set Authentication Mode to MD5 when configuring the IPsec policy for the VPN connection on the cloud.
  1. Check whether the ACL rules are correct.

    If the subnets of your on-premises data center are 192.168.3.0/24 and 192.168.4.0/24, and the VPC subnets are 192.168.1.0/24 and 192.168.2.0/24, configure the ACL rules for each on-premises subnet to allow communication with the VPC subnets. The following provides an example of ACL configurations:

    rule 1 permit ip source 192.168.3.0 0.0.0.255 destination 192.168.1.0 0.0.0.255
rule 2 permit ip source 192.168.3.0 0.0.0.255 destination 192.168.2.0 0.0.0.255
rule 3 permit ip source 192.168.4.0 0.0.0.255 destination 192.168.1.0 0.0.0.255
rule 4 permit ip source 192.168.4.0 0.0.0.255 destination 192.168.2.0 0.0.0.255
  2. Check whether the VPN connection is normal by pinging the local end from the remote end and pinging the remote end from the local end.
Parent topic: General Questions