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The Log shows "Received packet retransmission. Drop duplicate packet
10/14/2021 
76 People found this article helpful
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Description
The Log shows "Received packet retransmission. Drop duplicate packet.
Cause
The SonicWall received two identical packets and dropped one of them.
Resolution
Resolution for SonicOS 7.X
This release includes significant user interface changes and many new features that are different from the SonicOS 6.5 and earlier firmware. The below resolution is for customers using SonicOS 7.X firmware.
This log message is related to either TCP retransmission issues (for protocols such as HTTP) or the VPN configuration. It can be a Site-to-Site VPN, Client-to-Site VPN, L2TP or PPTP setup.
The following is a check list for troubleshooting Packet Retransmission messages:
- Check MTU settings- Navigate to Network | System | Interfaces | WAN | Advanced | Interface MTU.
NOTE: It is recommended to check the 'Fragment outbound packets larger than WAN MTU' if the MTU is set below the default of 1500. Use the 'Update' button to process the changes entered. - Fragment Packet Handling should be enabled.
- Pre-shared Key mismatch should be checked.
- Check the gateway IP address and firewall name or serial number specified in the VPN policy on each end of the tunnel.
- Lower the encryption settings.
- Check the upstream device configuration.
- Check for the NAT Traversal option.
- On the computer where GVC is installed, make sure the NAT Traversal option is disabled under Connection Properties --> Peers --> Edit --> NAT - Traversal.
Resolution for SonicOS 6.5
This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.
This log message is related to either TCP retransmission issues (for protocols such as HTTP) or the VPN configuration. It can be a Site-to-Site VPN, Client-to-Site VPN, L2TP or PPTP setup.
The following is a check list for troubleshooting Packet Retransmission messages:
- Check MTU settings- Navigate to Manage | Network | Interfaces > WAN | Advanced | Interface MTU.
NOTE: It is recommended to check the 'Fragment outbound packets larger than WAN MTU' if the MTU is set below the default of 1500. Use the 'Update' button to process the changes entered. - Fragment Packet Handling should be enabled.
- Pre-shared Key mismatch should be checked.
- Check the gateway IP address and firewall name or serial number specified in the VPN policy on each end of the tunnel.
- Lower the encryption settings.
- Check the upstream device configuration.
- Check for the NAT Traversal option.
- On the computer where GVC is installed, make sure the NAT Traversal option is disabled under Connection Properties --> Peers --> Edit --> NAT - Traversal.
Related Articles
- How can I configure a VPN between a SonicWall firewall and Microsoft Azure?
- Supported Public Cloud Servers/Instance Sizes on SonicWall NSv Series Models
- How to force an update of the Security Services Signatures from the Firewall GUI
Categories
- Firewalls > TZ Series
- Firewalls > SonicWall NSA Series
- Firewalls > SonicWall SuperMassive 9000 Series
- Firewalls > SonicWall SuperMassive E10000 Series
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