Hello,
I work for the "wifi support" of a large US ISP
Download a Wifi analyzer to your phone.determine what channel your wireless network is on and see if that wireless channel is also being used by multiple other wireless networks. If so, try changing it.
there are 3 different channels that you'd want to choose from.
1,6,11
everything in between overlap into the nearest channels. I can't word that any better but
1 does not interfere with 6 but 2-5 will interfere with 1 AND 6
6 does not interfere with 11 but 7-10 will interfere with 6 AND 11
12,13,14 are only allowed to be used in other countries(fcc regulations)
Also, check for other interference. (2.4GHz devices) such as coordless home phones, wireless baby monitors, RC remotes for model planes and cars and such.
Lastly, Check the placement of your wireless access point. Is it sitting on the floor, behind the tv, in a cupboard? In the basement? All of which are NOT ideal placements for your router.
Best placement is on top of a bookshelf or another high place where it has line of sight and in the middle of your house.
Wifi signals come out in like a "doughnut" shape. doesn't go up easily but goes outwards in a 360 degree circle and travels downward a lot easier than upwards.
Other things to check.
Make sure WMM is disabled. It is known to have adverse effects on clients and slowing them down.
Make sure legacy b is disabled (also known as BG protection mode)
Unless you have a b device that needs it
legacy b makes the router do a handshake ota before each transmission before the actual packets are being sent. If it's waiting for a handshake that doesnt need to be there then
1.) the router will wait longer than it has to since no b devices are present
2.) if other devices notice the router is waiting for a handshake from a client that isnt there, then all other clients will wait till they are free to talk.
Other than all of that and you arre still experiencing issues, do a FR on your router and if you are still having issues, then you may need an upgraded router then.\
Hope all of this info helps you or someone else reading.
further reading / watching
HAK5 Antenna Theory:
https://www.youtube.com/watch?v=MC0GuRgrVAM
HP Wireless overview (read section 5.2.3 RTS/CTS)
http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.mac.html