We have a B/G/N wi-fi network on D-Link DIR-620 rev. D1.
It works fine for 10+ clients, but when a particular laptop (HP Pavilion DV3 on Kubuntu 13.04) connects - some clients'
ping 126.96.36.199 (or even to a router) skyrockets from 40ms to 2-3s or more.
The slowed clients are - one Linux laptop (Dell 7720/Ubuntu 13.04) and one Windows PC w/TP-Link USB wi-fi card.
The offending laptop doesn't load the network at all, as per
ifconfig shows no lost packets even when disconnected.
1st channel was pretty busy. Moving to a free 13th channel didn't help.
How do I diagnose the problem and how can I fix it?
*I know of similar cases fixed by replacing a network card, but this doesn't look like a network card problem, rather a compatibility issue. And it's not the first guest laptop this happens to.*