Question Why is my internet speed dropping on wifi devices?

[PotatoLover]

So the thing is, my wifi speeds keep dropping BUT only on wifi connected devices. My PC gets full internet speed. It happens usually in the evening and at night. Things that I have tried :
1.Changing router location
2.Changing Wifi Password
3.Changing the router
The speed drops to the extent that the mobile/laptop shows limited connection even though router shows that internet is up.
Edit : I TOTALLY FORGOT TO MENTION THE MOST IMPORTANT THING. I use Tp-Link, and when the speed issue occurs, i also can't open the router portal properly. It is like some speed issue. (The signal strength is always strong)

 

[Moribund]

How old is the router and what's the model? It is possible that the frequency you are using is overcrowded when other people come back home. Have you tried switching the channel? Have you tried using 5 Ghz rather than 2.4 Ghz which has 20 channels rather than 3?

 

[Moribund]

Here https://www.tp-link.com/ca/support/faq/1217/?utm_medium=select-local or
https://www.tp-link.com/us/support/faq/2292/

 

[jsmithepa]

Yup, top of my head, NOISY NEIGHBORS. When this happens u may want to reboot the WIFI router, it then should automatically seek the better? channel under those conditions. No guarantee.