Wifi Issue on All Phones on Network

[Android Central Question]

We have 4 phones that are regularly connected to our Wifi but recently they seem to have gotten slower that usual. Instagram and Snapchat sometimes don't ever load but if I do a speed test on the phone it isn't low. When I turn my data on everything is fast like it should be. This problem effects all phones on the network but not computers or smart tv's so I was wondering if there was any way to pinpoint the problem.

 

[Rukbat]

Try changing the wifi encryption between TKIP and AES (in the router). At one point, my Samsungs couldn't handle TKIP for anything faster than a page of text. Whichever you have, try the other. (If you have TKIP+AES, change it to AES first - it's better from a security standpoint.)