Noticed something.. I was moving files on the LAN from a PC with 1Gbit adapter (Intel) to a laptop with 100Mbit (Realtek), through an Asus RT-AC68U Gigabit router; at the same time I was in a game online and noticed a huge latency spike and decided to check, from 50-60ms it went to a steady 700~ or so for most of the transfer duration. Router QoS settings are set to "Gaming".

What's happening here?

1) Shouldn't QoS give priority to the game packets?
2) Even if that wasn't working, the host PC sending the files is only using about 10% of the Gbit link bandwidth, why the huge latency?

Note: host PC is a decent machine with 16GB ram, i5-2500K at 4.3 Ghz running Win10 Pro x64, SSD

Maybe a problem with my motherboard? (possibly related to this https://superuser.com/questions/1126826/high-pitch-squealing-sound-during-disk-load-operations). The mobo is a middle-range Asus ($150) with Z68 chipset.

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  • I'd suggest your router just can't handle it, most can't. Also, just because your router is prioritising packets, doesn't mean your local nic is. – djsmiley2kStaysInside Dec 7 '16 at 8:33
  • There is a big chance QoS only works on layer 3. Packets between the source and destination PC are only switched in the switching part of the Asus. Why would the problem be related to the 'High pitch squealing sound' post? – mtak Dec 7 '16 at 8:34
  • Router is a $170 high-end Asus model, CPU usage around 1% during the transfer (checked on the router's admin area) – hikari Dec 7 '16 at 8:35
  • mtak: might be related as I suspect something's wrong with the SATA interface on this mobo (that other issue still unresolved) – hikari Dec 7 '16 at 8:39
  • Your router’s QoS isn’t in play here at all. Your “big transfer” is completely internal. If both devices are connected via Ethernet, the router’s CPU doesn’t even see the traffic. – Daniel B Dec 7 '16 at 8:50

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