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-   -   openvpn only using half of my upload bandwidth??? (

psycroptic 12-20-2012 05:27 PM

openvpn only using half of my upload bandwidth???
i have an openvpn setup that is hosted on a 50mpbs down/10mbps up comcast business connection. doing a test transfer of files from the vpn server to another machine on the same LAN results in near-wireline speeds (gigabit network, realistic throughpu is ~950-990 mbps). But when connecting over the internet, transferring files from the local LAN to teh remote client is a terribly slow 3-4mbps? I don't understand why... it can't be the CPU speed or anything on the VPN server, and if I setup a test FTP server unencrypted, I can max out my upload bandwidth perfectly with that. Please help, I've been so close to having a perfect VPN setup for months now but have gotten zero ideas as to why it's so slow.... I have played around with mssfix/fragment options (tried 1428,1400,1300,1200) but of course that had absolutely no effect.

nikmit 12-21-2012 06:57 AM

You are saying it can't be the CPU on the VPN server but still it would be the first thing I check.
After that speed check the link with a UDP based transfer (you can use nc or mz). Check it using the ports you use for your VPN setup - this should expose any trafic shaping on the link.
I guess the MTU on the VPN server will be adjusted automatically so this shouldn't be a fragmentation issue, but may be worth a look.

That's all I can think of atm :)


psycroptic 12-21-2012 03:19 PM

fyi the cpu is an intel core 2 duo 2.4GHz... i would guess that this is more than enough, considering openvpn apparently can run on el cheapo linksys routers...

psycroptic 12-26-2012 04:20 PM

so more info....

i've narrowed it down to what seems like a wifi issue. when I connect on an ethernet connection on the remote end, I can get normal bandwidth transfers (~9.6mbps, or 1.2MB/s) but when I'm on a wifi connection (even if its a fast 35mbps down with no one but me using it) I get my bandwidth cut in half, maxing out at around 3-4mbps. is this normal? surely just the act of being on wifi shouldn't reduce my bandwidth by 50%?

psycroptic 12-28-2012 04:03 PM

no suggestions at all?

psycroptic 01-01-2013 05:51 PM

i have since tried an entirely different computer as the openvpn server... core i3 3.3GHz 4GB DDR3 RAM. Not a thing has changed. SO it can't be the cpu.

psycroptic 01-02-2013 12:57 AM

even more updates:

tried removing the router entirely and going directly from the VPN server to the cable modem. Obviously I couldn't access the rest of the LAN, but a remote connection into the VPN server and a subsequent iperf test from a connected client to the server yielded 2.85 megabits per second, where the client was on ethernet on a 25mbps down connection.

so i've ruled out the router as well. i'm about to give up...

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