Wireguard half the down speed since upgrade to 21.02

[mietz]

I'm running OpenWRT as VM on my Proxmox Host. I've been doing this for some time but recently I discovered since updating from 19.07 to 21.02 I got a huge performance drop wenn using my wireguard connection. I made a 2nd vm with the exact same specs and installed debian and setup the mullvad client. in debian I get ~100 Mbps down, in OpenWrt its only ~40-50 Mbps down. IRQ Balance is installed, the debian results are matching the ones from 19.07 and my setup (pkgs/config) has not changed. Is this a known Issue?

root@OpenWrt:~# ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.136)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by ropa GmbH & Co. KG (Frankfurt) [3.81 km]: 20.915 ms
Testing download speed................................................................................
Download: 48.36 Mbit/s
Testing upload speed.....................................................................................................
.Upload: 28.16 Mbit/s
root@OpenWrt:~# ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.136)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Netprotect (Frankfurt) [3.81 km]: 21.046 ms
Testing download speed................................................................................
Download: 48.18 Mbit/s
Testing upload speed......................................................................................................
Upload: 28.40 Mbit/s
root@OpenWrt:~# ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.136)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Netprotect (Frankfurt) [3.81 km]: 20.985 ms
Testing download speed................................................................................
Download: 49.83 Mbit/s
Testing upload speed......................................................................................................
Upload: 28.26 Mbit/s
root@OpenWrt:~# curl https://am.i.mullvad.net/connected
You are connected to Mullvad (server de7-wireguard). Your IP address is 185.209.196.136
root@OpenWrt:~#

WG-Test:~$ ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.134)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by MK Netzdienste (Frankfurt) [3.81 km]: 30.355 ms
Testing download speed................................................................................
Download: 90.21 Mbit/s
Testing upload speed......................................................................................................
Upload: 30.30 Mbit/s
WG-Test:~$ ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.134)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by Netprotect (Frankfurt) [3.81 km]: 29.743 ms
Testing download speed................................................................................
Download: 87.17 Mbit/s
Testing upload speed......................................................................................................
Upload: 30.16 Mbit/s
WG-Test:~$ ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.134)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by MK Netzdienste (Frankfurt) [3.81 km]: 30.573 ms
Testing download speed................................................................................
Download: 90.45 Mbit/s
Testing upload speed......................................................................................................
Upload: 30.26 Mbit/s
WG-Test:~$ curl https://am.i.mullvad.net/connected
You are connected to Mullvad (server de7-wireguard). Your IP address is 185.209.196.134

[jhonnydeppends]

I hope not, have you tried it with openvpn to compare?

[mietz]

Here it was suggested that it has to do with the new DSA: https://www.reddit.com/r/openwrt/comments/r2nzm0/wrt1900ac_v2_wired_performance_decrease_on/

I believe this is due to the new DSA not supporting multiple cores, so that WAN and LAN have to share the same 1Gbps cpu port. In swconfig you can assign eth0 to LAN and eth1 to WAN, however in DSA you cannot do that (I think it’s by design?) even though you can see eth1 in DSA config.

There seems to be some discussions on this and upstream is trying to merge multi-core support patches, but I’ve not followed the development lately.

I also enabled packet steering without luck.

[mietz]

Lowering the MTU from default 1420 to 1380 brought the performance back!

root@OpenWrt:~# ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.133)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by ropa GmbH & Co. KG (Frankfurt) [3.81 km]: 20.767 ms
Testing download speed................................................................................
Download: 93.50 Mbit/s
Testing upload speed......................................................................................................
Upload: 30.07 Mbit/s
root@OpenWrt:~# ./speedtest
Retrieving speedtest.net configuration...
Testing from 31173 Services AB (185.209.196.133)...
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by ropa GmbH & Co. KG (Frankfurt) [3.81 km]: 20.554 ms
Testing download speed................................................................................
Download: 92.80 Mbit/s
Testing upload speed.....................................................................................................
Upload: 30.12 Mbit/s

[jhonnydeppends]

Cool ill bookmark this, so this is something they will fix soon then? Was hoping to max my vpn speeds with wireguard.