I’m trying to resolve a strange problem: I’m not a tech person, but I’ll frame it as best I can...
I have Fios 400/400 using a new TPlink Archer4000 router. When I run a speed test, the speed is where it should be. But: with two iOS devices, an iPhone X and an iPad, it always takes several seconds to establish a connection to a website or another service, like WhatsApp.
Examples: when I open WhatsApp, it’ll say “connecting...” for 5 or 6 seconds before it connects. Then it works fine. Or, if I click a Google News link to an article, it takes a long time to start, then loads quickly.
It’s almost as if something is blocking the connection for a few seconds and then when it goes through everything works normally.
In all cases the problem vanishes if I turn off WiFi on my iOS devices and use LTE.
I looked, and QoS was already off. I played with the frequencies a bit, trying channels 1, 6 and 11 in the 2.4 GHz band. I thought I had some improvement for a while in each case, but the connection delays came back eventually.
Next thing to look at is if there are any obstructions like metal walls or slats, microwave ovens or any other electronics around the router. If not place the router in a different location.
if your router has MIMO settings insure they are turned on and see if that fixes your issue. I would also if the router has external antennas place them to be upright and at least one slightly to the left or right to send a beam.
another thing to try is in your wifi on your devices to first forget the network then rescan for it and connect at the best signal ratio. 2.4 Ghz or 5 Ghz just remember some devices cannot connect at 5 Ghz and only use the 2.4 Ghz band.
as a last resort try another router or even a midrange router to see if that has better wifi. But I just looked at your router and it does have external antennas of which maybe try to place up high on the wall (I did this to my Netgear nighthawk) and it was a great improvement.