RT-AC68U WAN to LAN speed on a Gigabit fiber connection: Only getting 300 Mbit down

[arganis]

I've had this problem since I bought the router a month ago were I only get ~350 Mbit download speed and ~900 Mbit upload speed on a Gigabit fiber connection. I'm currently in touch with an ASUS representative and they just gave me a new firmware to try, but it unfortunately didn't fix my problem. To keep this simple, let me present the facts:

• Before AC68U I had a N56U which gave me ~900 Mbit up and down.
• Bootloader: 1.0.1.7
• FW: 3.0.0.4.376_xxxx
• Factory settings
• No USB devices connected, only two wired (CAT6) computers (LAN1, LAN2)
• Setup is as follows: Inteno FG500 (bridge) fiber converter LAN1 > AC68U WAN, AC68U LAN1 > PC

Is there anything I can try to fix this problem, I'm open to any suggestions!

 

[jlake]

You've tried resetting asus router to default and using default settings to ensure hardware acceleration is enabled?

You've disabled IPv6 to see if it's an IPv6 problem?

You've checked to see if you have proper MTU?

Edit: there's an assumption that you've already tried unplugging the modem and router for 10 minutes from the electrical outlet. And you've called your ISP to see if there's any special procedure you need to do when changing routers.

 

[arganis]

You've tried resetting asus router to default and using default settings to ensure hardware acceleration is enabled?

You've disabled IPv6 to see if it's an IPv6 problem?

You've checked to see if you have proper MTU?

Edit: there's an assumption that you've already tried unplugging the modem and router for 10 minutes from the electrical outlet. And you've called your ISP to see if there's any special procedure you need to do when changing routers.

Reset: Yes.
IPv6 is disabled by default if I'm not mistaken.
MTU is set to default 1500 (1492).
I've unplugged both devices (modem and router) but probably not for ten minutes and, yes, I have contacted my ISP and according to them everything is fine from their side and they don't need me to configure anything manually.

I get gigabit speeds from the modem (built-in router, see: http://inteno.se/store/tabid/141/categoryid/130/productid/771/default.aspx) and with my older N56U (modem>N56U) but not with the AC68U (modem>AC68U). There is another thread about a similar issue on the AC66U but without a solution: http://forums.smallnetbuilder.com/showthread.php?t=12973&page=5 The last post mentions a bug with his modem but I don't see how that would be a problem for me because my older router (N56U) works just fine.