Installed in a residence to transfer the signal from one floor to another. On a 500/250 mbps fiber optic line, as a wifi repeater its performance is in the range of 350-390/190-220, depending on where the mobile device is located. From the PC with wireless connection, wifi, 200/150. As a repeater again but distributing from the ethernet ports to a PC, the performance increases to 430-500/180-225. Especially the latter surprised me a lot because with a wired Devolo magic 2 Lan wifi next it did not go above 250/230 and because the position where it was installed is much more difficult for wireless signal reception. I have not tried it as an access point, with a wired connection to the router, because there is no need, the router's wifi fully reaches the line speed when operating as 5GH on the same floor. I consider it a very good purchase, with a slightly high but not unjustified price. Additional information: speed measurements with Xiaomi 15T pro. There is a big difference, when I record speeds with my tablet, they are noticeably lower.

Absolutely masterful little machine.

I have Cosmote fiber optic, and supposedly it reaches speeds of 300 mbps download, 150 mbps upload. However, for some reason, in practice I was generally facing connection issues and my phone kept disconnecting every so often, videos would freeze, etc., even though my router is on the same floor about 10 meters away (although we have thick concrete walls, so maybe that plays a role).

So I got this particular repeater hoping to finally see proper internet speed. Before connecting to it, I was getting 76 mbps download. Afterwards, I had to put my phone in airplane mode the first time and then turn it off to connect to the repeater (since I hadn't changed the settings and it had the same name as the same network), something that's evident from the Devolo app (it didn't show the phone as connected to the repeater before, but to the regular router), and the very next test I ran after it connected properly gave 285 mbps!

In general, I tested it in various positions and distances, and even at the farthest point in the house from the router with two closed doors and concrete walls, it gave me 256 mbps download and 150 mbps upload, in a spot where without the repeater I simply couldn't get any usable signal. The maximum download speed I've achieved so far is 295 mbps by bringing it, let's say, 4/5 of the way towards me from the roughly 10-meter distance I have from the router.
I haven't noticed a single disconnect from the internet since I installed it.

Installation is super easy, for first use you just download the app and it tells you step by step what to do (basically you just place it at the recommended distance, ideally in a socket without other devices, and hold down a button to connect it to WiFi for the first time), then as long as you want the same repeated network you just unplug it and move it to another part of the house if you want to change its position, just wait two minutes for it to reconnect.
The device itself has lights that show how many WiFi bars the repeater is getting (even with 2 out of 4 it's excellent signal to boost), as well as some other device statuses that you can read about in the app's reference manual.

Generally perfect so far, definitely better than any other extender I've tried, so I'll say it's worth the money (I bought it for about €140).

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It should be noted here that I haven't tested it yet via ethernet cable, as a review I read refers to this method as by far the best, but I will update when I test this as well.

As a repeater, it does its job just fine without disconnections and with satisfactory speed. As an access point, I wouldn't recommend it; there's no difference from the provider's router (speedport plus 2), it doesn't offer anything extra. Of course, if you have an old WiFi 5 router, you will definitely see the difference, otherwise it's only worth it for use as a repeater.

Update. 14/09/2024
At a distance of about 15 meters and from the first floor where the router is to the second floor where I have the Devolo. With an ethernet connection from the computer to the Devolo, I get the full speed that the router would give me and even more as shown in the photo. Also, the measurements from the mobile with wifi connection to the Devolo are just amazing... it's like I'm next to the router, with an almost negligible increase in ping.
My line is 300 fiber.
Stable speed without any disconnections.
Worth every euro and more!!!!
You buy it once and you have peace of mind.

update 14/07/2025
What are these €650 and €400 prices, guys? You have completely lost it. No, guys, at €160 when I bought it, ok, yes, it's worth it, but at the price it has reached nowadays, not even close. It doesn't have diamonds inside, just so you know.

Until now, I was using a NETGear (old model EX3800) which I had reviewed and rated as excellent. However, my internet speed has been upgraded to 200 mbps and I am preparing for 1000 mbps through a full fiber optic network. This extender was choking the speed despite the fact that it still had great coverage and never disconnected. After reading the reviews, I bought this Devolo and... miracle, I saw the real light! The installation was extremely easy, even for kindergarten kids. You press WPS on the router, press the corresponding button on the extender for 2-3 seconds and... that's it! It connects in a flash. I was even surprised that it didn't come with a manual in the box, just an illustrated card with basic instructions that turned out to be unnecessary. Speed? On my tablet's wifi connected to the router (remember, network speed is 200 mbps), I was getting 26-30 mbps, with the old extender only 10 mbps, and with the Devolo... 170 mbps!!! Signal? Perfect everywhere. What else can I say?

IMPORTANT NOTE: This extender does not have a built-in plug to directly connect to the socket, which is not clear from the photos. It has a power supply that needs to be connected to the socket and a cable to reach the extender's port, so you need to make sure there is a table near the extender to place it on.

NOTE 2: The use of this extender also led to an interesting situation. I am a COSMOTE subscriber and I use the Speedport plus router. Before the Devolo, I had the NETGear (mentioned in my review) and before that, I didn't have an extender. My mobile phone was constantly connected to my home's WiFi and its battery consumption was unreasonable. It would start at 8 am with 100% charge and end up at 10% by 11 pm, needing a new charge, without heavy usage. I thought it was the battery's fault, but searching on the internet, I found out that others had the same issue with the Speedport plus. After using the Devolo, I noticed a significant improvement in the battery's duration. Specifically, where I used to reach 10%, now I'm at 35% or even better. I don't have an immediate explanation, but the difference is so big that I can't help but mention it.

First of all, let me say that I work from home and the distance from the router to my office is quite large. Also, due to the layout of my house, my WiFi has some “dead spots” where the signal doesn’t reach well and I had quite a few disconnections. So far I have bought 3 different brands of WiFi Extenders/Repeaters. So I believe I have a good opinion on the subject.
Devolo (this particular model) is the 3rd brand I am trying. I consider this WiFi Extender/Repeater to be the best I have tried so far. Its price at €135.71 when I bought it is steep (for a repeater).
First of all, its setup is super easy. You don’t need to have… a PhD in WiFi (!)… to connect this repeater. You just plug it in, press 1 button… and it does everything by itself. If you use the app, you have control over even more advanced settings (but you don’t need to go into those). It’s perfectly set up by pressing 1 button. Nothing like the setup of my previous ones. It can be set either as a Repeater (Range Extender) or as a WiFi 6 Access Point. I use it as a Repeater. Honestly, I haven’t encountered an easier setup.
Anyway, everyone manages the setup (even with a lot of hassle). In practice now… Where I saw a huge difference is in performance. Honestly, it eliminated the WiFi dead spots in my house. Now I have stable signal everywhere. And with WiFi 6 speeds. I also tried turning off the WiFi from my router completely (standard Vodafone router) and used it as an Access Point. It worked perfectly. Even if the router is not WiFi 6, the wireless connections between devices and the Extender/Repeater are at WiFi 6 speed. Don’t overthink it… this is it!!!! I consider it by far the best Extender/Repeater I have tried so far.
On the negative side, I would mention 2 things. A) its high price and B) the lack of an auto power off schedule setting every 24 hours.
But despite these 2 negatives, its excellent performance doesn’t allow me to give it less than 5*.
UPDATE 07/06/23: I have Fiber To The Home (FTTH) internet from Vodafone. I have connected the Devolo WiFi 6 Repeater 5400 to the standard WiFi 6 router provided by Vodafone. After almost 2 months of intensive use, I am completely satisfied. The performance is flawless. By far, the best repeater I have bought. In my 140 sq.m. apartment I have WiFi everywhere and even WiFi 6. I highly recommend it.
Of course, there is one DISADVANTAGE. I consider its price at €135.71 (that’s how much I paid for it), very expensive for a repeater. It is quite high, hence the -1 star.