Firstly, when manufacturers mention 300 Mbps or so in wireless, that is the theoretical speeds. Getting them is usually as good as sitting nearby to the WiFi AP, with nearly no other devices and zero interference. In reality, consider that max speed you will get, even when you are only using the WiFi is 50% ie 150M. Then, you are affected by distances as well and the radios/antennas of your devices. This is where MIMO and separate antennas come in.
If you want speeds of nearly 100M, you have 2 choices, get dual band routers, and ensure you get the USB/PCIe dongle which supports dual band with separate/detachable antenna. This will allow you to ensure you get higher speeds
Next, if the device is too far away, you need to invest in a repeater if you do not want to do wiring. I would suggest to find a way to do the wiring instead. Optionally, if you can spend more, look at mesh devices - TP Link/DLink are cheapest, cost about 15K for a set of 3. Otherwise, look at powerline adaptors.