【Typical Case】How to Troubleshoot a Windows PC Experiencing Slow Internet Speeds After Connecting to L2TP over IPsec VPN on an NBR Router

Keywords:

VPN, Slow Internet Speeds
Issue Description

When the Windows PC is not connected to the VPN, the internet speed reaches 200 Mbps,but it drops to only a few tens of Mbps once the PC is connected to the VPN.
1. Device Model and Firmware

Device Type	Device Model	Firmware Version
Reyee  NBR router	NBR6215-E	NBR_RGOS  11.9(6)B17P3, Release(11161700)

2. Cause Analysis

By default, when a Windows client connects to an L2TP over IPsec VPN or L2TP VPN, all traffic—including normal Internet traffic and traffic to the VPN headquarters—is routed through the VPN tunnel.
3. Solution

The bandwidth of a VPN tunnel is typically limited and shared by all connections,so routing all data through the VPN tunnel is not recommended. Consider the following methods to address this issue.





By default, the Use default gateway on remote network checkbox is checked.When a VPN tunnel is established, both the device’s Internet traffic and VPN traffic are routed through the VPN tunnel.
Uncheck the Use default gateway on remote network checkbox, then disconnect and reconnect to the VPN.