Wifi is faster on WAN than LAN?

[binarydad]

I'm trying to figure out why this is. I have a AC68U and noticed that for wireless devices only (such as my Galaxy S8), if I run fast.com or speedtest.net, I'm getting around 350-400mbps, but when running a local LAN speed test (such as Wifi speed test pro), I'm getting around 300mbps. I can confirm this by looking at the traffic manager in my router. Both cases are me sitting next to the router.

I've tried resetting the router, resetting the switch that sits between the router and the server I'm running tests against. Gigabit LAN transfers are full speed (110MB/s) - it just seems to be with wireless transfers on WAN vs LAN. Nothing is necessarily wrong, but am curious to why my WAN speeds on wireless are seemingly faster.

First orange test is LAN, the second orange is WAN (fast.com). Thanks.

 

[SoCalReviews]

There could be a software firewall or other performance limiting factor on the LAN device causing the slowdown.

 

[doczenith1]

I would use iPerf3 to test your LAN speed. I'm not sure how those other apps work but the one I tried a few years ago was not accurate at all. I use Magic iPerf on Android. For testing this is the command line that gave me the best results for the client.
iperf3 -c 192.168.1.xxx -O 5 -i 5 -w 4M -t 30