I set up my VPN on the router, so as to route ALL of my network's internet traffic through the VPN. It worked, at less than half speed.
That is, I have a 100 MB fiber connection, and the highest speeds I saw on the VPN was about 50 MB up and about 35 MB down. Sometimes speeds were as low as 25 and 20.
Deleting the VPN, and installing the vendor's own software on both a Windows machine, and a Linux machine, I see consistent speeds around 90 MB up and down, on both machines. Devices not routed over VPN see consistent speeds of 93 to 95 MB down, and sometimes as high as 115 MB up.
I've done a number of searches on the subject, and I've not found very satisfactory answers. One expects slightly slower internet when using a VPN, and that is what I see when VPN is installed on individual machines. I lose ~10% of my speed.
Why would I lose 50% to 80% of my speed when VPN is installed on the router? Is it the limitations of the CPU? Or, maybe, is there a known problem with the DD-WRT build I am using?
Should I maybe upgrade to a newer build, and try again? Or, perhaps there is an older build that I should try?
I should note that everyone in the house is happy with the current setup, VPN running on the two critical machines. But, I may wade back into the setup sometime, (in a week or six) and get it working on the router.
The OpenVPN speed you see is normal for such low end equipment (ARM A9, 1 GHz).
Alternatively use WireGuard which should give you over 100 Mb/s or use a router with more CPU power.
My R7800 does about 85 Mb/s on OpenVPN and about 280 Mb/s running WireGuard
Awesome reply. You confirm most of what I suspected. I can fix the old build easily enough. The weekend is just about here, maybe I can get that done tomorrow. Can't fix the underpowered CPU unless I get another router. I may just do that, but not immediately.
I switched over to Wireguard, and yes, I'm seeing a major improvement over OpenVPN.
Now, I have to admit to a little bit of stupid. I got the R8000, over an available 7800, because, bigger number.