GT-AC5300 Gigabit internet limted to 200 Mbps

[ToMaSoo7]

Hi,
I just upgraded from 200 Mbps to 1000 Mbps internet but I'm stuck at 200Mbps while using GT-AC5300
If I connect my computer directly to modem I'm getting full speed(well, around 900Mbps) but when I connect to GT-AC5300 I'm getting exactly 200Mbps.

All LAN connections are 1Gbps(Modem to router and router to PC).
Resetting router to Factory default didn't help, still 200Mbps

Is there some settings I need to change? Or what can be the issue?

Using latest FW 3.0.0.4.384.81695

 

[karma]

disable QoS

 

[ToMaSoo7]

Never used QoS, is disabled.

 

[ToMaSoo7]

I found this thread with similar issue:
https://www.snbforums.com/threads/rt-ac5300-slow-internet-speed.57837/

He fixed it with different modem, it seems weird to me.

 

[wouterv]

Given you use the same PC and same network port of that PC to connect to either the router or the modem:
I suspect the cable between the PC and the router.

 

[L&LD]

And if it's not the cable, try a cheap and cheerful switch between the modem and the router.