For your budget, I think the newer Deco X80 from TP-Link is a better choice.

The twin pack model is sufficient. Contrary to popular believes, more mesh points aren't always better in mesh Wi-Fi as they causes interference and backhaul issues.

If two units can provide sufficient coverage, always go for 2 units.
I will suggest getting 2 units of ASUS routers.

Configure the first unit as the router and the second unit as the AiMesh node in your room. Then, connect your XBOX via LAN cable to the second unit.

This will get rid of bufferbloat or congestion issues that lead to ping spikes and lower your latency as well.
That's a really huge property

I will suggest the Deco X50-4G and pair it with 2-3 units of Deco X20 to have full Wi-Fi coverage at your property.

Since it's a mesh Wi-Fi, you enjoy all the benefits of seamless roaming one just one Wi-Fi name throughout the entire property.

If you prefer something budget friendly, get the TP-Link MR500 4G modem router.

Doubt you needed the Mikrotik since you have pretty decent 4G signal. I will recommend that if you stayed at somewhere really remote or you have an unlimited budget. 

If budget is not really a concern, I will like to use at least 2 units of RT-AX86S or above.

Just remember it will not be any faster than using a direct Ethernet LAN cable.

Giving with current 500 mbps and my Ax3000 being crap, I need a decent router that can transmit 500 mbps on mesh as well..

I'm down between Ax53 and Ax55. Since Ax73 cannot mesh with the same unit

In term of mesh compatibility which one was better?

Your router also needs to support 160MHz in order for your WiFi card to utilize it
Not all router supports 160MHz bandwidth

My mind just pop out this issue after making purchase of TP-Link Deco XE75 yesterday (haven't received)

So what i learnt is that 6Ghz can be wireless backhaul and SSID at the same time but the 6Ghz will be like a separated SSID toward 2.4/5Ghz.

Question: Meaning to say that if my Wi-Fi 6E devices connecting to 6Ghz SSID will not be able to see devices connected to Wi-Fi 2.4/5Ghz ?
Example if i want to chromecast (google) or screen mirror (ios) from my Wi-Fi 6E devices to TV (connected with non-Wi-Fi 6E). It will not see each other cause differ SSID

iOS will prompt a warning if 6Ghz is different name with 2.4/5Ghz as well

Best practice nowadays is to use same name

SSID should be identical these days

I dun have Iphone 15 pro series (only series with Wi-Fi 6E) with me though.

I do have few Wi-Fi 6E devices at home so i can just rename the 6Ghz as same SSID with 2.4Ghz/5Ghz so the client will auto switch it self ?
Mesh router normally combine into one SSID (2.4Ghz and 5Ghz) so the client can auto switch whenever it's strong signal exclude Wi-Fi 6E default with "_6ghz" index behind
if rename to all same meaning sort of "combine" and client will auto detect and connect.
Create a guest network with only 2.4Ghz
But now router has those "IoT network" separate out SSID

I prefer the router and client auto switch themselves XD

Further range auto switch to 2.4Ghz and vice versa

While most of my IoT using guest network with 2.4Ghz for stable link

Wait XE75 come and see how adjust later 

Only issue is my x20 is v1 which does not support IoT network (only v3 and v4) which is a bummer for early adopter 

Sifus,

I'm using Asus TUF AX4200 as the main router, located at ground floor.

Also having a Huawei EchoLife WA8021V5 set as AP, wired to the Asus, located at the back of upper floor.

Both set with the same SSID.

My issue is, my S23U phone can switch to the Huawei and connectivity works fine.

But when I go downstairs, it switches back to Asus but without internet.

What is the problem here?
Do I need to change the SSID for the AP?