Nobody has reported the issue yet, so if 2.4GHz is a lot faster then you'd need to report the issue here. But the report needs to be as detailed as possible, since it's not enough to say that 2.4GHz is a lot faster when using the proprietary MediaTek driver.
- Use the same WiFi settings on both firmwares
- Disable 5GHz and limit the 2.4GHz mode to N on both firmwares
- Share the contents of
/etc/config/wirelessfrom both firmwares - Share the log file from both firmwares
- Input
iw phy0 infoand share the output from both firmwares - Perform online speed tests with both firmwares
- Perform local iPerf3 speed tests with both firmwares
The title should be something like "MT7986: Slow 2.4GHz WiFi compared to proprietary driver".