Mesh with ethernet backhaul (connect ethernet cable from one unit to the other) since the house is just next door.

AX is definitely overkill, for 30mbps AC is more than enough. Back then when I just upgraded 5mbps to 30mbps Unifi (VDSL2 copper line), I keep getting disconnections and turn out the line attenuation in my building is quite bad (not something I can control). TM eventually said they fixed it somehow but later still keep dropping connections. I changed my router to a TP-Link C6 (AC1200 speed) and it's all good ever since.

Is this normal?

The loaded latency is at 358ms! That 20X the unloaded latency.

In term of user experience, you can feel the internet speed is not stable.

So I've got a weird situation, just installed TP-link wifi mesh in my home. First few days of using it, my pc got a speed boost, speed test reaching 85 mbps, I can even go to certain websites without using VPN. But since yesterday the speed now went down to my regular 35-45 mbps and I got blocked from those certain websites again. Anybody can help explain what happened?

SMB file transfer is a TCP protocol and it scales horribly when high latency is involved. Your dual-band system is probably terrible at handling congestion.

Just do a ping test and see how high is your latency when you are transferring files.

Hence, that's why newer mesh Wi-Fi in the market focus less on raw speed but more on congestion management these days.

yeah sometimes microsoft also fk up the smb speed in some windows updates recently

are your pc on windows 10 or 11?

I thought you are using MR8300 with WHW0101?

Anyways, those older mesh are notoriously bad at congestion management which will lead to poor SMB transfer speed.

Just FYI, Asus official store on Shopee gives much lower prices than this during their date.month sales, no need to trade in anything also. On 9.9 I saw the TUF AX-6000 for around RM650, if memory serves.