Slower than expected wan speed with RT-AC66U when connected to ISP fiber router

[Quiller]

Since last Friday I am connected to my new fiber optic internet connection which offers 500Mb up and down. I still use my RT-AC66U as my main router and have the wan port connected to my ISP's router.

I've noticed however, that I'm not getting 500Mb up and down when my computer is connected to my Asus router. It's able to do around 214Mb down and 402Mb up, but I am getting 500Mb up and down when I plug my computer directly into my ISP's router.

Is this a known limitation of this router when it's connected to another router?

Has anyone tried this with the new RT-AC88U and is getting max speed (like 1000Mb up and down) when connected to another router. I'm planning on getting this router, but if this router has the same limitation, then I probably won't.

 

[tsunami2311]

is QOS on or any other feature that would disable nat acceleration

 

[Quiller]

QOS is off and I dont't know what other setting switches off nat acceleration. It says CTF is enabled under the LAN - switch tab.

 

[tsunami2311]

Enable Jumbo Frame
NAT Acceleration <--- if off speeds will be bottlnecked
Spanning-Tree Protocol

are only setting in there for AC66U

 

[Quiller]

NAT acceleration is on, so I'm guessing that this slower speed that I'm getting is due to a hardware limitation.. I just want confirmation.

 

[Hinker]

I myself have a 1G up/down FTTH, My AC66U is connected to a modem not a router and I get around 850Mb down and 900Mb up when only testing and nothing else run.
I even tried over clocking the AC66 but that didn't do anything so just running standard clock.

When I'm directly connect to the modem with my laptop I get around 940Mb up and down.

So 500mb should be within reach for the AC66.

I'm running John's Fork as I think that works best for me.

 

[petya]

On my 100 Mbs pppoe connection the AC66 can keep up but I don't think it can handle anything more then 200Mbs.
In top cpu usage for sirq is very high when the connection is maxed out: CPU: 5.9% usr 2.8% sys 2.5% nic 0.0% idle 0.0% io 2.5% irq 86.0% sirq
CTF is shown as enabled but something seems to be wrong. I have upnp enabled and a few nat passthrough options enabled also. At the moment the router is running on merlin 378.56_2.

 

[Quiller]

I changed to the new Asus RT-AC88U router and now I'm getting full bandwith. I suspect a reset to factory defaults would have been enough, but I was going to get the RT-AC88U anyway, so I set that one on my network.

 

[jegesq]

The AC66U is fully capable of keeping up with your bandwidth, but since you purchased a new AC88U, perhaps we'll never know. You are probably right to suspect that a reset to FDS (factory default settings) and then re-inputting your settings manually would likely have resolved whatever the issue was.

And since you don't have the same issues with the AC88U, you can likely rule out any issue with your ISP-supplied modem, but I'm curious that you describe it as an "ISP's router". What brand is it, and is it a simple modem, or a combo modem/wifi unit? If the latter, I trust you have put it into "bridge mode" and turned off DHCP so that your AC66 or AC88 are acting as your router and the ISP's device is acting only as a modem. If you're not in bridge mode on that device, that could easily explain the issue (but it wouldn't explain why you're not seeing the issue on your AC88U).

You might also consider re-purposing your AC66U as either a Repeater or Media Bridge, or as an AP if it is practical for you to run Cat5 or 6 cabling to it. I have two AC66's that work great for me with an AC3200, one as Repeater the other as a MB.

One last thing: Turn off upnp; it's just a security hole waiting for someone to exploit it, and its entirely unnecessary in 99.9% of use cases.

 

[petya]

I have disabled URL filter and keyword filter and IPTraffic. QOS is also disabled.
What else affects CTF, what else should I disable/enable considering I have a pppoe connection.
LE.: I installed Johns fork and this FW seems to better manage soft irq-s. I also disabled spanning tree protocol since I don't need it.

 

[petya]

O Johns fork my AC66U was rebooting itself every 6 to 8 hours so I tried disabling CTF. For now I can get by without it and it seems it solved the reboots also as my up-time is over 21 hours now.

 

[mstombs]

...
One last thing: Turn off upnp; it's just a security hole waiting for someone to exploit it, and its entirely unnecessary in 99.9% of use cases.

Do you set manual port forwards for all users with games/skype/torrent etc then? I agree some devices that implement a full upnp spec allowing configuration of dns servers etc is over the top, but Asuswrt uses miniupnp which has a number of sensible security enhancements such as restrictive port ranges and 'secure mode' - which restricts clients to only setting their own port forwards. I wouldn't be without it!

 

[Hinker]

O Johns fork my AC66U was rebooting itself every 6 to 8 hours so I tried disabling CTF. For now I can get by without it and it seems it solved the reboots also as my up-time is over 21 hours now.

Did you do a factory reset after update and manually entered all settings? Just that I have seen reports where this was not done or a restore of a settings file from the old fw version.
This could produce different errors perhaps like this one?!

 

[john9527]

O Johns fork my AC66U was rebooting itself every 6 to 8 hours so I tried disabling CTF. For now I can get by without it and it seems it solved the reboots also as my up-time is over 21 hours now.

CTF can be a bit finicky with certain ISPs, particularly on the MIPS based routers when used with IPv6. If you need the CTF support and are using IPv6, the other thing to try is to disable IPv6.

 

[petya]

Did you do a factory reset after update and manually entered all settings? Just that I have seen reports where this was not done or a restore of a settings file from the old fw version.
This could produce different errors perhaps like this one?!

Of course I did the reset to factory defaults, it was the first thing I did. I understand it can be the source of many problems but it is not a magical solution for all of them.

CTF can be a bit finicky with certain ISPs, particularly on the MIPS based routers when used with IPv6. If you need the CTF support and are using IPv6, the other thing to try is to disable IPv6.

I managed to stabilize the router and have CTF enabled. I still see high soft irq cpu usage when connection is maxed out but I stopped worrying about it. These stability problems are a pain in the butt to debug because it takes a long time.
I changed 3 things:

1. took the router and the external hdd of a ups and now they are plugged directly in to the mains socket.
2. disabled ipv6 for now. ISP provides native ipv6 for their pppoe connections. I had ipv6 enabled from the first day and had no problems but I had to take it step by step.
3. Trafic stats are now saved to RAM. I had these set to be saved o a second partition ext3 on the external hdd. The hdd has a spindown timeout of 120 seconds.

Next I plan to change the battery in the ups and put everything back on it and if that is OK then I'll enable ipv6.
I'll leave the traffic stats for last.

 

[ancorrea]

Hi, thanks for your reply. The asus rt 88u is connected an ONT Alcatel Lucent I-240W via PPoE.
- I connect the rt-88u to the modem wirelessly. If I connect via ethernet it says the cable is disconnected, even though is a good cable (cat6).
Thanks