Good day Asus Malaysia & all friendly LYN member 

I've been using ASUS RT-AC68U for few months and it's been working perfectly. But just yesterday i noticed the LAN speed (connected to my PC) suddenly capped at 100mbps max.

*Fyi, i subscribed to UniFi 500mbps, and all the while i'm getting full speed (500mbps) on my PC with Ethernet connection.

Below are the things that i found :

1. At first i noticed my Ethernet Status speed is getting 100.0 Mbps, so i thought it's caused by the Speed & Duplex set to 100mbps capping. (it's configured with Auto Negotiation.)



2. I checked my Ethernet Ports status on Asus router configuration, all the LAN port are getting 100 Mbps (which i believe Speed & Duplex is not the root cause).

Is the status supposed to be like this? (I can't recall the speed on all port previously but i think it should be 1Gbps? Please correct me if i'm wrong)



3. Here's my router firmware version :



Few other troubleshooting steps I've done :

a. Change the Speed & Duplex from 100 mbps to 1.0 Gbps Full Duplex (not working)
b. Turn on Adaptive QoS and set the download speed to 500mbps (not working)
c. Turn on Jumbo Frame from LAN - Switch control (not working)
*All the things above I've never done before, my router and ethernet properties are in stock settings (I did not change anything previously).

Additional information :

a. I'm able to get the expected speed with WiFi 5ghz speed test on my phone (close to router).
b. 3 of my LAN port are connected to :
- LAN 1 > My PC (which should get 500mbps)
- LAN 2 > My another Asus Router (serve as an Access Point)
- LAN 3 > My CCTV DVR
- LAN 4 > Empty
c. All the cable are CAT6
Hope i posted in the right place. Any help and advice would be greatly appreciated !