Xiaomi AC2350 slow 5Ghz Wifi speed

Hi. I have ~400Mbps connection. And on a stock firmare I always get around 380Mbps on 5Ghz WiFi. However with OpenWrt it's never goes over 150Mbps.. I tried everything I could think of..
Any advice?

Yes: give some actual details on what you have tried and what your settings are. We can't magically just see your settings or anything.

I’ve tried all available WiFi chanels, tried updating all packages on a router, tried reseting router, toggling different options under 5GHz network settings..

Did you try enabling Packet Steering?

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Tried right now - nothing changed.

SSH in to the router and run cat /etc/config/wireless.

Redact the passwords in the "option key" sections.

Post the results in preformatted text, by using the icon highlighted in red...

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config wifi-device 'radio0'
	option type 'mac80211'
	option path 'pci0000:00/0000:00:00.0'
	option band '5g'
	option htmode 'VHT80'
	option cell_density '0'
	option country 'CN'
	option channel '153'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'OpenWrt_5GHz'
	option encryption 'psk2'
	option key 'xxxxx'

config wifi-device 'radio1'
	option type 'mac80211'
	option path 'platform/ahb/18100000.wmac'
	option channel '1'
	option band '2g'
	option htmode 'HT40'
	option cell_density '0'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option ssid 'OpenWrt'
	option encryption 'psk2'
	option key 'xxxxx'

Channel 153 at 80 MHz width overlaps with 6 other channels.

As a test, you might try 40 or even 20.

I would also use a WiFi analyzer app to see who is using what channels in your area, your signal strength, and your signal-to-noise ratio (SNR).

The stock firmware probably used hardware NAT, which is currently only supported for MT7621 devices on OpenWrt.

Your also limited by the 775 MHz CPU, so you're likely top out around 200 Mbps.

You might also try the ath10k-ct-smallbuffers or the ct-htt firmware.

Thanks for the instructions, tried everything. But as you've mentioned, because of CPU I'm probably stuck at that speed limit.