Openvpn Slow Download Fast Upload Updated -

If your OpenVPN is configured to use TCP, you are likely experiencing "TCP-over-TCP". When a packet is lost, both the tunnel and the data inside the tunnel try to retransmit it at the same time, causing a massive traffic jam that slows downloads to a halt.

If your device (especially a router) has a weak processor, it may struggle with the heavy decryption task required for fast downloads while managing the upload just fine. OpenVPN slow download | Netgate Forum openvpn slow download fast upload

By default, OpenVPN often uses small socket buffers (historically around 64KB). While this is fine for low-latency local networks, it creates a "bottleneck" on high-speed internet connections. Data arrives faster than the small buffer can process it, leading to significant download slowdowns while the upload remains unaffected because it isn't hitting the same limit. If your OpenVPN is configured to use TCP,