WiFi loading all content very slow on every WiFi device

[Gandek]

Recently upgraded my Comcast internet from regular 25 MB/S to a 75 MB/S plan. We got a new Router/Modem combo as well, before we were using a old separate modem and router which constantly had the internet disconnecting. It's been fine but a week later my device and my dad's (Both S7) are barely able to load anything over WiFi we tried to reboot etc. but nothing seems to help. Downloading anything over the play store is also impossible. On Speedtest we still get normal speeds like were supposed to but somehow if i switch over to data (4G LTE) i get 1MB/S in my house but everything loads much faster compared to WiFi... i simply don't understand this, anyone who knows how these networks work i will really appreciate your help

 

oh and the modem/router combo i got looks like this  http://pisces.bbystatic.com/image2/BestBuy_US/images/products/9082/9082028_rd.jpg;canvasHeight=500;canvasWidth=500

[InVis]

That sounds a lot like interference.

Have you tried switching channels on your wifi modem/router?

 

It might also be that the DNS replys are slow.

You can try to set the DNS manually in one of your phones to 8.8.8.8 for example and see if that makes any difference for you.

Most CPEs will resolve the DNS query for you and sometimes the thing that makes the internet seem slow, is the CPE due to it being too underpowered to handle being a router, switch, modem, dhcp server and dns relay server.