I spent something like two or three hours trying to diagnose this weird latency issue
Every four or five seconds, any traffic on my laptop's nic would just... get delayed for 2.5 seconds.
I went through the wireless config, tried changing channels, tried power cycling the router, but in the end the problem was with the laptop.
It was waiting to complete a cumulative update installation and was being weird
I spent something like two or three hours trying to diagnose this weird latency issue
The problem was, the laptop was the only device connected to the AC router, so I didn't have a quick way to compare/contrast its behaviour
aaaaannyway, it's work fine now