Uiii, please don't buy a range extender, it's useless. To optimise the WLAN in your own home, you can use a WLAN mesh router system. Range extenders are a technology of the past, they only cause problems, halve the throughput in the worst case and you gain nothing. WLAN devices hang on to the router or range extender until the connection is completely lost. From this point of view, you don't gain anything with these devices. Better are so-called mesh WLAN systems, which consist of many (or a few) small routers that communicate with each other and build a network. Devices can be moved within the network without interruptions. A mesh system passes the devices from a weaker mesh router reception to the next stronger router without interruption and the setup is also very easy, compared to range extenders you gain a very good coverage and more throughput with a mesh router. I would recommend the TP-Link Deco M4, it costs little more than outdated range extender technology, but offers very good coverage in your own four walls with WLAN signal.
TP-Link Deco M4 AC1200 Dualband WLAN Mesh 2-pack
A Deco Mesh system can also be expanded later without any problems if necessary, but to start with I would try two. There are more explanations here, it's really easy (in contrast to Range Extener):
https://www.tp-link.com/ch...