Cause the lan port on E4R is only 100Mbps. So the speed will capped at 100Mbps no matter what.

You need to upgrade to better router to get rid of speed cap

That's why it is cheap for a reason.

Return it and up budget a bit get x20 or above

I just google search, only 100mbps port
Cannot solve it

Try to sell in garage sales or mudah.
Avoid Deco E series as limited to 100Mbps port.
M5 or M9 Plus much safer.

Your home can do wired backhaul or not?

If can do wired backhaul: M5 will be good enough for up to 500m
But is old model

So i suggested up a bit for X20 above for wifi6 future proofing (wifi6 can easily reach over 500m)
If cannot do wired backhaul, your budget must be up much higher. For triband system to work without speed deterioration. Even M9 plus will barely usable for 500m. X68/X90 or Asus XT8 not cheap

Hardwire both of 2 mesh units with ethernet cable

I think what you ask means your home is not ready for wired backhaul because your home has no ethernet cable / point installed during furnishing

Get your budget ready

E4R no matter wired or wireless is capped at 94m because is hardware limited by its fast ethernet 10/100m port. By now tplink should not sell this shit anymore to "坑" buyer

Main deco M4R can with other E4R only on wireless backhaul

And expect lower speed with this model. True stori

my home m4r can barely get 300m from main unit. Down to around 150m if from second unit

X20 yes for future proofing

But if you want buy single unit for gigabit port I recommend M5 single unit to try out first. After when you get wifi6 capable devices and want more then only you consider upgrading to x20/above

Take note that any deco model can join your home system easily. So M5 can work with E4R. Later can add X20 or whatever model to either replace or as add on to your deco system

X20 yes for future proofing

But if you want buy single unit for gigabit port I recommend M5 single unit to try out first. After when you get wifi6 capable devices and want more then only you consider upgrading to x20/above

Take note that any deco model can join your home system easily. So M5 can work with E4R. Later can add X20 or whatever model to either replace or as add on to your deco system

Yes
Just make the gigabit version (M4 or M5 etc) as main one connected to modem will do

care to share what not ideal is and the misleading and hided information that you found?

The biggest problem with powerline is the poor wiring quality in Malaysia. They also suffer a significant performance loss when used with three phase power.

Some inferior power adapter, surge protector system will cause interference with powerline signal as well.

The best powerline I tested can only perform around 200Mbps. Any decent mesh WiFi system will outperform that easily.