So does this mean that using 5ghz bandwidth i can achieve higher speed when i am upstairs as compared to 2.4ghz? And I guess upgrading my router will improve the situation? As my current one doesnt even have external antenna

I am thinking of getting the ac1200g+ as that doesnt cost that much and is similar to the ac1300uhp. What do you think?
Ah my bad indeed that was repeater mode. So for client mode must connect ethernet to pc?
That time is was my parents who setup the fibre cable and they chose the living room as it is nearer and dont need to pull the fibre so far as there will be extra charges and I was still small that time dint know anything

Set up a few AP in repeater mode?

As for router, I am thinking of getting the ac1200g+ as that doesnt cost that much and is similar to the ac1300uhp. What do you think?

Are there any options other than client mode? As I dont want to route cables here and there.

I tried powerline adapter before. Langsung cant use in my house. Not sure if its because of 3phase wiring.

Ok ok then I shall get a better router. RT-AC1300UHP the best bet? Any other options I can consider?

I am on Unifi 50Mbps and is now using Asus RT-AC55UHP router. It is working fine most of the time with no issue of connection lag, except when my brother kids comes home in the weekend.

On most days the router only has about 5 devices connected to a maximum of 7 devices.

Times when my brother comes back with his family, the router will see about 14-17 devices connected, due to my bro, his wife and the kids connecting to the wifi also.

That the time when the RT-AC55UHP start becoming slow. I do not think it is the line getting over saturated or bandwidth usage issue. As i have been monitoring the router WAN interface for some time and notice utilization is fairly acceptable hit about 60% on average. The issue is the CPU of the router staying at close to 100% all the time, the kids is all an avid fans of streaming video online (watching youtube mostly).

So if you are like me, expecting lots of devices connecting (in excess of more than 10), i would suggest getting a router with higher cpu clock rates or more cores.

So i am now on the hunt for a router with higher cpu clock rates and has more cores, to see if i can alleviate the issue of connection being laggy.

It would also help in your own selection criteria, to read up on some of the newer router features. Example like beam forming, MU-MIMO / SU-MIMO and etc. Those will help in choosing a right router for your home.