Cisco AnyConnect VPN kills download speed

Advanced feature discussion, beta programs and unsupported "Labs" features.
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by fgaillard » Mon Apr 22, 2019 6:36 pm
I have fiber at home and get routinely ~930 Mbps for download and upload.
But when I connect to work with Cisco AnyConnect VPN (the one I have to use to get to company network), the download speed is massively degraded down to less than 270 Mbps.

Now I can understand that adding a layer would not improve speed, but there are 2 things I find weird:
1. When disconnecting and quitting AnyConnect, the download speed does not come back to normal; I have to reboot.
2. Only the download speed is affected, the upload stay consistently above 920 Mbps

[OTN]--[Pace 5268AC]--[Asus RT-AC88U]-<[wired laptops]

If I connect directly a laptop to the Pace 5268AC, I get less of a drop (down to the 500 Mbps), but otherwise the same symptoms.

So it seems that going through each router after having activated AnyConnect is roughly killing the download speed by 2 each time.

What could i try to remedy it? (like for downloading some big 40 GB file from work at full gigabit speed)
What could I do to regain the normal speed without rebooting each time?

Any idea welcome...
by bubba198 » Mon May 27, 2019 7:53 pm
If I could clarify, the download speed degradation you speak of happens to public targets, yes? NOT measured between you and any of the networks piped via the VPN tunnel?

I use AnyConnect too and I can not replicate your observation meaning whether I am connected or not my is pretty much the same.

Obviously a good test will be to connect your laptop to another Gigbit network and compare results, few Starbucks do have real Google Fiber but most call it "Google Fiber" and pipe it via Comcast Business delivered via coax service LOL

The one guaranteed is Walnut Creek downtown on Locust :) Good testing ground

by fgaillard » Fri Jun 14, 2019 6:49 pm
Yes, I measured the download speed degradation with the various speed test websites (including Sonic).
But I did the testing to begin with because some downloads (inside the VPN) seemed to be slower than what I expected.
I do not have access to tools to measure speed within the VPN.
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