According to the dimensions of the House, but also according to the subjects that comprise the walls of the House, and interference waves, the scope of the wifi can unfortunately quickly decrease! To rectify this, there are different ways:
- place your router as high as possible and a place or there will be less interference (for example turn a pc just next door, in a piece of furniture, etc…)
- change wifi channels to reduce interference
- no longer use WiFi
- destroy your walls
- use the method of the ricoré wifi antenna
- steal the neighbor's wifi
- use an amplifier
The wifi amplifier I tested is WF – A7 AC 750 at Aukey. 
Features
- 3 multidirectional antennas
- Broadband: Wifi standard AC
- Dual Band: 2, 4 GHz and 5 GHz
- 2, 4 GHz to 300Mbps
- 5 GHz to 450 Mbps
- 3 modes: amplifier, router and AP (access point)
- Easy apparaiment WPS button
- 1 port Ethernet Wan + 1 port Ethernet Wan/Lan
- Dimensions: 7.25 cm by 5.05 cm (without antenna)
- Universal compatibility
The test
The first thing that you can say when you unpack, is that it is small! It does not exceed 10cm! And yet, half the size is taken by the antennas! Th
anks to its size, this small router/modem/amplifier is both portable and… not portable! Transportable because of small size, and not portable because the antennas are not unscrwable! A shame! About these antennas, they can turn on themselves on 180 ° and be "folded" to 45 ° and 90 °. In short, give a very good coverage, especially since they are 3! In addition to 
the 3 antennas, you have a button ON / OFF on the left side, and a reset button. On the right side, you have a switch with 3 positions for the different modes:
- AP mode: in french, access point, is used to make the connection wired ethernet available in wifi. Basically, it's a wired relay-> wifi
- Repeater mode: so, the amplifier/Repeater mode. Take a wifi network and amplifies it. Basically, a Wifi relay-> wifi.
- Modem mode: allows to replace the modem of your ISP.
On the front, you have a WPS button to facilitate the connection between 2 devices and 7 mini leds:
- Strong wifi signal
- Average wifi signal
- Low wifi signal
- WPS
- WAN/LAN
- LAN
- Power
On the underside, you have 2 Ethernet ports. Because of its small size, everything is concentrated and the amplifier heat on each side has air holes. No fan incorporated, so silent. The heater can be a problem, but the modem from my ISP, which is 5 times as big and great, heats much more for less features… and still holds the road well what lit h24 and fanless. About the configuration, it is fairly standard to access: Once connected in wifi on the amplifier, go to 192.168.10.1 or . The configuration is intuitive, the software is well done, is not complicated and is quite complete. 
This amplifier has allowed me to double (or almost) the range of my wifi (2, 4 GHz and 5 GHz). Of course, since it is dual band, it can issue 2 frequencies at the same time without worries. About the reach of wifi, it is important to know where to put the amplifier: in one place or one captures very well the wifi you wish to duplicate! Why? It is relatively simple: the more you move away from the emission source, months signal strength is strong and the quality goes down. It's a bit as if someone were speaking: If the person is next door, there is no problem to hear it. If the person is 1 meter, it should still go. If the person is 2 m, it's getting harder to hear, especially if there are other surrounding sounds. Wifi is more or less the same principle. If you want to hear what the person says and you have another person who properly relay the information, must this relay well hear what the 1st person said! So, that makes that in reality, you can't double the range of the wifi with a duplicator! The scope will always be less than double if you want a good quality. Of course no need to put the amplifier right next to your modem, otherwise, the scope will be the same as the source, with a bonus a possible interference! In addition, keep in mind one thing: If you plug it into an outlet built into your wall, you "lose" already 1/4 of the total coverage that can give you your amplifier due to your wall! (Requires power supply built into the wall) Therefore, less there are barrier nearby, better. And higher, better it is also. It's like the antennas of telecommunications as radio/gsm/etc… they are always placed as high as possible for the best range for must see waves in 3D, they spread more or less 360 °. If they are close to the ground, you have a loss on the horizontal plane.
Conclusion
A very good amplifier / adaptor of wifi networks. Fairly complete with its 3 antennas, dual band 2.4 GHz and 5 GHz, standard AC, 750Mbps of total bandwidth. Fairly comprehensive software. In short, to be a good wifi connection to hates flow without too much trouble. On the other hand, due to the miniaturization and the absence of built-in fan, place it preferably in a well ventilated. Link: https://www.amazon.fr/R%E9p%E9teur-300Mbps-AP-Compatible-Amplificateur-Wall-plug-Blanc/dp/B01DF6YHH2 also note that there is an improved version, in 4 antennas that offers a better bandwidth in 5 GHz (not tested, all seem to have the same size, so the main question to ask is "what happened to the heat released?"): https://www.amazon.fr/gp/product/B01HG1MKBW/ 