@ndrprs 

Hey

Just reading your descripton of the problem of the slow speeds.   At a guess this is the powerline in your home causing this issue, namely the quality / distance of the powerline is restricting you to ~150mbps.  Moving the plugs around might get this faster for you

Powerline speeds are very much like WiFi speeds, namely you are never going to get the full 100% speed of the plugs, usually the average is around 30/40% of advertised, but again this can be lower.

I would recommend you download the TP Link PLC app and get an idea of what speeds your powerlines are connecting at, the app will tell you the actual connection speed.   Should this be coming in at ~150 then that is your problem.    Below is a pic for example of the app

If I am totally honest with you, 1GB home fibre is a very very fast connection and I am getting more and more calls from customers who are having the same issue as yourself.  In the vast majority of cases they have tried a MESH or HomePlug setup and while it works OK, its not giving them the full 1000 speed.   300/400 seems to be the common speeds they indicate

The only method you are going to get anywhere near the full 1gb speed is to run cables, if you need or want fast as possible WiFi look at the Omada EAP245 or EAP6xx series access points.  Even with these business grade device you will get ~700 at best over WiFi (WiFi6).    Cable will always get you the full 1000

Download the app first and then we will know more.

@Philbert 

Thank you for your answer.  The problem is that even running ethernet cables I have the same issue, the connection speed is just a little bit faster.

The TP-Link PLC app reports ≃500Mbps.

@ndrprs 

Hey

When you say running a network cable do you mean from your Laptop / Desktop straight to the router?

What speeds do you get if you are not using the home plugs?

@Philbert 

No, I mean running a network cable from my laptop to the powerline's gigabit ethernet port (and getting no more than 150Mbps).

When I connect the laptop directly to the router I get a speed between 800 and 1000 Mgbs.

@TP-Link 

Hi, thanks for your answer.  I updated the drivers and I tried the connection via ethernet after plugging the two adapters next to each other.

The TP-Link PLC app reports ≃ 800Mbps, but the speed reached by the device was ≃ 200Mbps  (via ethernet cable).

I believe the only problem is the powerline's gigabit ethernet port, because the Wi-Fi connection improved a lot when I plugged the two adapters next to each other.

P.S.  Can I ask you another question?  Considering a distance between the router and the socket of 6 - 9 metres (without walls), is it better using a range extender or a powerline kit in terms of Wi-Fi speed reached by the laptop?  Thank you again for your help.

@ndrprs 

I believe the only problem is the powerline's gigabit ethernet port, because the Wi-Fi connection improved a lot when I plugged the two adapters next to each other.

Just be careful in that it will misread the speed the same way the cable connection will.   Your Cable could be connected at 1000 (it likely always will be), your WiFi at 866 but ultimately the transfer rate between the plugs is the bottleneck here.     Think about it like 2x  4 lane motorways connected joined by a 1 lane middle section, you will do full speed at both sides but ultimately the middle will be your slow part..

As TP Link confirm its around 30/40% of hte connection speed is the norm for homepugs (and also WiFi).    However network cables 99% of the time give the full speed

P.S.  Can I ask you another question?  Considering a distance between the router and the socket of 6 - 9 metres (without walls), is it better using a range extender or a powerline kit in terms of Wi-Fi speed reached by the laptop?  Thank you again for your help.

If its 6-9 meters a good WiFi should suffice for you, if you can get connected at 866mbps expect 300/350mbps real speeds.   Homeplugs will likely be a tad slower in general over that distance, however they are a more stable connection.