WiFi slow on OpenWrt? (Linksys WRT1200AC)

[IvoK]

I have two identical routers Linksys WRT1200AC. One runs OpenWRT and the other DD-WRT, both in the latest stable versions (for OpenWRT that is 21.02.3 r16554-1d4dea6d4f). My WiFi is set up exactly the same way in every respect on both routers, same modes, same channels, same channel width, same transmit power, same beacon interval, same security etc. When I test the WiFi speed on e.g. my iPad using first one then the other router (both the routers and the iPad in exactly the same position) the speeds achieved are significantly lower on OpenWRT. For the 5 GHz network the DD-WRT values are around 350/90 Mbps while on OpenWRT I get 90/70 Mbps. The latency and jitter are very similar on both routers. The 2.4 GHz network behaves in a similar manner. I have also checked with other devices (iPhone, two different laptops) and the finding is always the same.

Any idea why this is?

[frollic]

nm, clueless

[hnyman]

@frollic

drivers for the Broadcom radios.

...while wrt1200ac has Marvell mwlwifi.

[hnyman]

@IvoK

same security etc.

The mwlwifi open source driver is somewhat crippled.
Especially some security combos cause trouble.

Avoid wpa3 and also 802.11w (management frame protection)

[IvoK]

That was it! Only disabling the 802.11w didn't change anything. Then I also changed the encryption from WPA2-PSK/WPA3-SAE Mixed mode to WPA2-PSK with forced CCMP (AES) and now I'm getting the same speeds as with DD-WRT. If after this change I switch to WPA3-SAE, the speed remains the same (high). However, if I switch the WiFi off and on again on the client device, the device has difficulty detecting the network. Many thanks for your help!