R6400 slow wifi speeds, but wired speed is ok

[RJHarris]

Suddenly a few days ago, my wifi speed really nose dived. Getting wifi speeds of 4.35 mbps and similar 1 digit readings

I rebooted my modems, but it didn't help. So I rebooted the router, still didn't help, but I found a speed test on the router.

Ran it and had 300+ mbps speeds. So I found an old CAT cable and wire the laptop to the router. Still 300+ speeds.

My speeds did increase slightly for my wifi, like in the 50 mbps range.

Any ideas as to why there's such a difference?

[plemans]

What firmware is on the router? 

What modem/gateway is it connected to?
Did you check to see if you're connected to 2.4ghz or the 5gh? 

did you try changing the wireless channels in case there's interference? 

Or did you try a factory reset?