Help please with a Belkin RT3200

I have installed this version on my Belkin RT3200 Router as shown in the screenshot, but since I did it the Internet speed through the 5G WiFi is very low. I read that you have to install irqbalance and the QoS package but I've only installed them, I'm not sure if it's enabled, let alone configured.
Can someone please tell me the steps to follow to improve this, I don't want to have to go back to using the stock firmware because I have noticed that with OpenWrt the internet is much more stable despite being slower.

Update to 22.03.5, or 23.05 RC2, to start with.

I've already updated to 22.03.5, I didn't know there was a newer version available. After doing it, without keeping any changes, I have done a speed test and I have the maximum speed allowed at the moment. I have to change my adapter to WiFi 6 to finish testing. But for now good. Thank you!

If you have any suggestions or additional configuration that you recommend, I appreciate it.