What factor most affects VPN speed?

Hi all,

I have a program on the office server that I'd like to use over VPN. The client software is on my laptop and the actual program and database is on the server. The problem is that the program is extremely slow over VPN, to the point of being unusable.

I have tried contacting the program developer for assistance, but their answer is "we do not support use of our program over VPN". Now I don't know whether that means it cannot be used over VPN or they just don't support use over VPN, but that's all the answer I'm getting.

My question is, is it possible to speed up the VPN connection so I can run the program as fast as if I was in the office? Is there a bottleneck I can try to open up? I'm brand new to VPN connections, so I have no idea what details you all need in order to help me.

Thanks all!
6 answers Last reply
More about what factor affects speed
  1. Really VPN throughput will be limited by the following items:

    1) Network speed in general. If you're trying to run it over a really slow link then it will be really slow :-)

    2) Processor power / encryption algorithms in use. Some older network equipment and consumer level gear simply cannot perform encryption at a very high rate of speed. What are you using as end points, what type of VPN (IPSec, PPTP, L2TP?)

    3) You may have something configured incorrectly with the VPN. Give us some details on what VPN setup you're running... are any other applications running correctly over the VPN?

    Also what protocols does this program use? I'm assuming most likely tcp or udp....
  2. Well... kinda depends on how much bandwidth he's trying to push... and I meant CPU as in he could be maxing out his router / firewall appliance, which sometimes aren't exactly beefy.
  3. Thank you dadiggle and brian_tii!

    Here are some details on the server and network setups:

    - Windows Server 2003
    - P4 2.4GHz
    - 3.25 GB RAM

    - AT&T DSL
    - Download speed: 4.39 Mbps
    - Upload speed: .43 Mbps
    - Firewall is in use
    - VPN setup was with PPTP
    - dadiggle, not sure what "socks" is and whether or not the program on the server supports it.
    - Regarding other programs used over VPN, I haven't tried anything else out yet. I can say that opening a Word doc or a file folder on the server can take quite a bit of time, around 5-10 seconds. But at least it opens, as opposed to the program which takes about 5 minutes to open.

    Thanks again!
  4. Thanks dadiggle, I forgot what exactly I have, just a standard Netgear router.
  5. kampana said:
    Thanks dadiggle, I forgot what exactly I have, just a standard Netgear router.

    I'd seriously considering going to something with a little bit more "umph" behind it. Those little Netgear routers have a lot of features but that doesn't mean they're necessarily well-equipped to do it. I have used these in the past and they overheat and drop packets like crazy, and that's just a standard application. VPN is going to greatly increase the load on the router and slow things down quite a bit. I see that as being your biggest bottleneck thus far. Second being your upload bandwidth.

    Hope this helps :)
  6. Thanks again dadiggle and PsychoTeddy.

    Is PPTP the best setup for a VPN connection? Also, I forgot to mention that the modem itself is about 10 years old. It's the original modem that AT&T (then PacBell) gave us when they setup DSL in our building. Could the modem be a bottleneck too?
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