Good for you. What brand/model homeplugs are you using? Maybe the current models are better.

I've tried in my uncle's and auntie's houses. Both on 3-phase. Low throughput, high latency and moderate packet loss. I was testing with my 2011 homeplugs, AzTech HL115EP 500mbps. I don't remember exactly but was getting around 10mbps in my uncle's house and around 50mbps in my auntie's. It's still usable in my auntie's house. Actually my uncle also using it. No choice for him. It's fine for Whatsapp.

In my single-phase house, I get 350mbps sustained throughput.

Interesting. Maybe your house wiring better or something.

Normally I test speed with iperf from one pc connected to one homeplug and to another pc on the other homeplug.

And ping or mtr for latency and packet loss. mtr is like PingPlotter.

mine is 3-phase electricity...i tried several power plugs and yet the download speed is even worse than my wifi
probably faulty wiring etc ...i dunno

I got the C1200, and now running okay I guess. 

Need to see what it could do later when I'm back this evening as I wasn't at home during the installation (only other occupants).

However, as I stay in a triple storey home, the internal Cat5e cabling is another issue for now.

I am using Archer C7. UniFi 50 Mbps here. The C7 i bought by myself after tm refuse to upgrade my old L7 router to c5 due to the warranty finish already. We paying them monthly and they don't even bother to change the equipment as the package increases. My old Asus RT-N14UHP shows signs of dying and I've to rely on the L7 router where the speed drops dramatically. Finally, opt to buy archer c7 by myself.

TM replaced the old DLINK router to DLINK DIR-850L (pic attached for ref).
I find the DIR850L 5Ghz signal very weak.
Also the router is not really that good, wifi signal is weak and also at times the router gets slow and needs to restart.

I am going to disable the 5ghz signal to reduce load on the router.

Wondering what router is TM giving now for 100mbps package customer.

i wonder if they will replace the router just incase if its broken to the C1200 

HINT heard loud and clear. Now let me check if they will replace without charge or any contract renewal.

Doesn't matter from where. It all adds up if it's a ram problem. Try running 5 well-seeded Centos torrents and keep track of the number of connections in your torrent client while monitoring the ram and cpu usage in the C1200. See when the webgui and the torrents start to slowdown. Once you find a pattern, you may be able to mitigate the problem by limiting the number of connections in your torrent client.

Below is an example. I was testing an RGX4400 to find the limits of the router. The RGX4400 also has 128MB RAM with about 60MB free at startup. You can see below that it handles 5 torrents with a total of ~1000 connections with no problem.

Did you find the problem?

You replaced your old-working-good-router with C1200? Didn't they ask whether your old router is working or not?

last time I called, they only allow to replace if my old router is faulty.

You can change your router anytime. Just call 100 and tell them that you want to change your current router to a new one.
You can create some stories. I told them that my WiFi performance is bad, and my internet speed is slow , need to reboot it everytime when it happens. Guess what? They didn't charge me for RM53.

about the same bro. its just that c1200 newer than C5. in real life performance, u wont feel any difference.

wireless 2.4ghz or 5ghz?
1) 5ghz are weaker than 2.4
2) 2.4 got lot of interference, scan and choose the right channel
what u need is an AP or extender to max your wifi range.

Yes C1200 got 3 antennas but still a 2x2 router.

for me single, USB is not an issue. but it would be nice if its USB 3

best solution is pull RJ45 upstairs and set another AP.