Thanks for the information.
Unfortunately, I don't think I can upload that 3rd party firmware for this router, I helped my landlord to install this router system so it could cover up to 4800 sqft spaces (And They only have internet cable on their basement's corner). And they have zero internet...
Just want to get this information out there, when I tried using my new bought RT-AX68U as an AiMesh node for RT-AX88U, the internet system required to use Dual-band Smart Connect for the whole system to work, otherwise, the main router(RT-AX88U) will show the node has a weak signal despite they...