Help! OpenVPN Clint Slow on Windows, Fast on Linux

reeco

I'm using the same client.conf on a Ubuntu desktop, Window 7 32 bit, Windows 7 64 bit, and WinXP. All from the same cable connection.

On the Ubuntu machine, speedtest.net averages 10MB down. With Win7 it's about 2-3MB down (regardless of windows version). On XP I'm lucky to get 0.5MB down.

Without the VPN connection, all OS version run at about 25MB down.

What could cause this?

Here's my client.conf

client
dev tun
proto udp
remote xxx.x.xx.xx 1194
resolv-retry infinite
nobind
persist-key
persist-tun
comp-lzo
verb 3
remote-cert-tls server

<ca>
-----BEGIN CERTIFICATE-----

-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----

-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN PRIVATE KEY-----

-----END PRIVATE KEY-----
</key>

reeco

Version on the server is: openvpn-2.2.2-1.el6.rf.i686

reeco

I tried changing to TCP with no improvement. I then ran some ping tests to find the optimal MTU which was 1400 in WinXP. So changed the TAP adapter settings to 1400 and disabled the firewall on this adapter. I then added this line to the client and server conf, and restarted openvpn.

fragment 1400
mssfix

Unfortunately that has not made any improvement. I'm still getting about 0.5mb download speeds on WinXP and greater than 10MB with the same connection on a linux machine.

Any suggestions on other things to test?

reeco

It might be a hardware issue. I'm noticing that when running the speedtest, if I open a new tab in the browser and am viewing the new tab, the connection speed burst up to 10MB. As soon as I go back to the tab running the speedtest, the speed drops back down after about 2 seconds.

Wonder what the issue could be here?

reeco

Ran out of time to edit the above... but wanted to clairfy that this issue is only when I'm connected to OpenVPN. Otherwise speedtest.net shows good speeds, regardless if there is a new tab open or not.

Laakkus

I have the same. Seems it might be a tap-driver issue

Lähetetty minun GT-I9300 laitteesta Tapatalkilla

ogghi

Hi there, I don't like to resurrect such an old thread, but I am experiencing the exact same problem.
PFsense with latest OpenVPN 2.4.9.
UDP server.
Linux machine gets full speed of the line, whereas Windows is always limited to around ~50Mbit/s.

Has there been any solution in the meanwhile?

lynspyre

Check this old post, it helped me, hope it help you too.