Slow VPN - IPSec, PPTP, OpenVPN



  • I'm running a pfSense box with 1.7Ghz P4 with 1GB of RAM. I'm connected to another pfSense box via ipsec and all works fine. The issue I have is all my data going out through the VPN is extremely slow. I have 18mbps fiber both ways and I only get ~1.5mpbs out through the VPN. The other pfSense box can send data to me at it's full bandwidth (5mpbs). I can upload files to others via web server, ftp, ssh/scp,..etc at full speed (18mpbs) with no issue, but can't get more than 1.5mpbs (146kb/s) out via VPN. I've played with several settings with no much luck. The is also reflected on the PPTP connections and OpenVPN connections. I haven't played with the WAN MTU, but changed "Enable MSS clamping on VPN traffic" to different MTUs and it doesn't make any difference. While doing a file transfer, the CPU is only 10% in use. Any ideas on what could cause that?


  • Rebel Alliance Developer Netgate

    Could be an MTU issue. Under System > Advanced on the Misc tab, try setting up MSS clamping for VPNs there, try something low-ish like 1400.


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