I don't need speed, just need to be able to use the computer in the living room. Right now, I only get good signal in the bedroom, the gloomiest room with the ugliest view.
For most apartments, a repeater is not needed with the proper setup. Devices further away from the router should be connected using the 2.4 GHz due to their range and better ability to penetrate through walls and other solid obstructions. Devices closer to the router can connect using the 5Ghz. Your router is likely dual band and can broadcast both at the same time. 2.4GHz is actually quite fast and enough for typical usage. I can stream HD videos on 2.4GHz on a TV that is in a room furthest away from the router, with four walls between them, one of the walls being solid brick.
1. Make sure your router is not on the floor and not directly against a solid wall. I put mine on top of the hutch on my desk.
2. Keep the router away from other electronic devices.
3. If you use a streaming device, make sure the USB power cord, which also acts as the antenna is directed away from other cables. I actually hang the USB cable vertically behind the TV, away from the other power cords and power strip. That was a huge difference. My FireTV stick loses internet connection once in a while before I moved the USB cable away from the other power cables.
4. If you have an unstable connection using 2.4GHz, try switching the channel to Channel 11. It might have defaulted to channel 6. You can also try channel 1 if 6 or 11 didn't improve the quality of the connection.
5. For those having connection problems between floors, try changing the angle of the antennas instead of leaving them just pointing up. Try 30 degree for example. If you cannot adjust the antennas because they are internal, you can try reposition the router itself.