I have openvpn running on pfsense, and is connected from alt location. A speedtest from alt location gives me ~250/250mbit on a laptop. A speedtest on the server will give ~900/900mbit. So internet speeds are ok.
When connected to openvpn, start a file transfer from a mapped network drive, speeds are ~11/15mbit. Openvpn is running on a qotom w. i3-4025U, and by looking at cpu usage, there seems to be plenty of headroom.
Could this have anything to do with “force all traffic” through the vpn? I normally have it off, but a test did not seem to change anything.
Secondly, when/if you switch on the “force all traffic” do you need to do anything client side, like reconnect, change a setting or other?
Check:
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TCP or UDP for OpenVPN? TCP can cause slowness
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Is compression enabled?
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Is the VPN using heavy encryption? (Blowfish recommended for fastest)
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Have you checked MTU values?
ping -f -l <size> serverStart with 1472. If you get fragmenting go up or down by increments of 10 . Add 28 to the largest number that does not fragment and test again. -
Does the MTU match on both sides?
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OpenVPN is single threaded. Check to see if you are getting a single core bottleneck.
Hopefully someone else with a better idea will be around.
This might be of help:
https://community.openvpn.net/openvpn/wiki/Gigabit_Networks_Linux
I am unsure about this.