The internet speed on my computer usually slows down when there are many devices using the wifi but is fine when wifi is turned off on these devices. Is there any way to improve my internet so that I don't have to turn wifi off on these devices? Do I buy a new router because my router is pretty old and if so which routers are best in each price range? And how do I replace the router? I don't know much about networking.
Devices: 1 laptop, 4 phones and 2 comps
Router: TP-Link TL-WR340G 54M Wireless Router
Modem: SB5101 SURFboard Cable Modem
Thanks