RT-N66U download speed half the upload speed on fiber

[blackholesun]

I have also seen that you need CTF enabled to see above 150Mbps in a speedtest on N66.

Yes you do. Unfortunately Shibby's FW does not have the CTF option available for N66U.

Is wan type simple dhcp of do you use a pppoe connection?

If simple dhcp it looks like a new firmware issue, if the cpu is at the limit every extra iptables check will reduce throughput, could also be how the router in the link gets the tcp/ip rwin pacing to be negotiated between server and client.

I tried both the latest 7410 and the earlier 3861 from Asus. Same thing.
My WAN settings look like in the screenshot. When I do speedtest, the CPU load under Status tab is showing 100% on download and upload.

 

[hggomes]

Do you have full speed when connecting only with ISP equipment?

 

[blackholesun]

Do you have full speed when connecting only with ISP equipment?

Pretty much.

WAN cable from ISP equipment directly to my laptop:

WAN->router->laptop

 

[hggomes]

Have you tested RMerlin FW or John FW instead ASUS Stock?

 

[blackholesun]

Not yet, will test it on Monday when my gamer son is at school

 

[hggomes]

Good luck.

Maybe you are double NAT in there, make sure thats not happening.

 

[blackholesun]

Maybe you are double NAT in there, make sure thats not happening.

Perhaps asking the obvious, but how do I check for double NAT?

 

[blackholesun]

Ok I flashed Merlin 378.55 it looks very nice.
Do I have to reset/ restore factory settings?

 

[hggomes]

Yes, i recommend it, also configure it from scratch, do not import any old configuration .cfg file.

If you see the same happening with your speedtest, try John FW its based on 374 old code (JUN 2014), that will show you how it performs 374 vs 378 code on RT-N66U regarding your issue.

PS: Have you checked for double NAT?

 

[mstombs]

Perhaps asking the obvious, but how do I check for double NAT?

With double nat you will have local IP as the WAN IP of the router, usually caused by a modem not in bridge mode.

 

[hggomes]

Sorry i missed your previous message, i guess mstombs already answer it.

 

[blackholesun]

Bit of an update.
My ISP has been having DNS issues, so I entered Google DNS servers to the router configuration.
Result!

 

[hggomes]

Some months later...