Enabling WiFi slows down NAT (bcm53xx)

Rafał Miłecki zajec5 at gmail.com
Fri Jan 13 01:27:23 PST 2023

On 12.01.2023 16:50, Rafał Miłecki wrote:
> The problem I recently discovered is that NAT slowes down after enabling
> WiFi. Without any actual traffic. I mean just enabling 2 APs:
> uci set wireless.radio0.disabled=0
> uci set wireless.radio1.disabled=0
> (it's a BCM47094 + 2 x BCM4366).

I was wondering what exactly caused that slow down.

I started with removing bridge interfaces (brctl delif) - didn't help.
Then I tried bringing interfaces down - didn't help.

I also tried netfid to handle things for me with:
uci set wireless.radio0.disabled=0
uci set wireless.radio1.disabled=0
uci commit wireless
(no result).

That was unexpected.

Finally (with radios disabled in /etc/config/wireless) I called:
/etc/init.d/network restart
and that finally helped.

Then I decided to reproduce manually the slow down.

That was simple. It's enough to call:
iw phy phy0 interface add ap0 type __ap
(without even bringing interface up!)

What's interesting - calling:
iw dev ap0 del
doesn't bring full speed NAT performance.

I need to call /etc/init.d/network restart to get back to the 940 Mb/s.

FWIW BCM4366 wireless chipsets are suppoted by brcmfmac.

Also "iw dev wlan0 set type __ap" doesn't slow down NAT. It's a new AP
interface that is needed.

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