I use TP-Link BE800 Router, After the upgrade to latest firmware, I noticed a significant speed drop over Wi-Fi all the band (5GHz, 6GHz, and MLO.), while the LAN connection remains normal. I tested with multiple devices, and the issue persisted consistently.

I also tested using another router on the same network (connected to the same upstream router), and no speed drop issues were observed there — which confirms the issue is specific to the TP-Link BE800.

To troubleshoot, I downgraded the firmware to the previous version:
1.2.1 Build 20250108 rel.48985(4153)

After the downgrade, Wi-Fi performance returned to normal with no more speed issues.
This leads me to believe the issue is related to the latest firmware version (1.2.3).

Please investigate this further,

Thanks!