@Winded My Pleasure 💓

@Capmkwifi Deco M4R has 1000 Mbps ports. You can check again after using CAT6 ethernet cable.

@Winded Yeah exactly i used HTTP method which is recommended by TP-LINK for Deco M4 and uploaded 1.8.2 firmware.

@Winded Yeah i have reverted back by using Recovery Mode from the link below and yes mine is also Deco M4 V2. https://www.tp-link.com/us/support/faq/2958/

@Winded I tried OpenWRT too but the 5 GHz wifi performance and range is very slow. I have also reverted to official tplink firmware.

@Winded Did u try to install official firmware directly from OpenWRT ? i think you brick your Deco M4.