N66U Sudden loss of speed (hard wired)

[Darren M]

I bought the N66U only 4 weeks ago. I'd been getting the full download speed (60 Mbps) that is provided by my ISP up until a week ago. All of a sudden I'm only getting about half that at 33 Mbps ish and it's very unstable. The PC I run the tests from is hard wired.

The ISP has been doing some work just recently, and prior to the reduction in speed I was getting intermittent disconnections from the internet. However, If I bypass the N66U and plug straight into the Modem I get the full 60 Mbps. Once the N66U is reconnected I see this 50% reduction in speed.

It's worth noting that another laptop in the house can get 45 Mbps from a upstairs, wirelessly.

Nothing had changed; no firmware changes, settings changes, and the ethernet cable is the same. I've tried changing all the cables and I still get the same results. I've now tried restoring the settings and changed the firmware, then loaded the settings back in, but I'm still seeing the same results.

Running latest Merlin fw .23b version.

Could this be a hardware fault?
Would it show up in the logs and what would I be looking for?

Are there any settings in the fw that could have caused this. Like I say though, nothing had been altered.

Any help would be greatly appreciated.

Thanks,
Darren

 

[Darren M]

Bought new Cat5e cables, but I'm still getting significantly better speeds wirelessly than I can achieve hard wired. Like I said, I get full speed if I cable direct to the Modem, and this has only changed in the last week.

Doesn't matter which PC I use either, results are always the same.

It's doing my head right in now.

 

[bluepoint]

Have you reboot the modem?

 

[Darren M]

Yes many times.

I have also cleared nvram via the wps button, and updated the firmware again to the latest Merlin beta version.

I'm on the verge of sending it back and bringing the old D-link 655 out of retirement. Never had these sorts of issues with the D-link.

This issue has gone 'one step beyond' - NAANAANAA-NAANAANAANAANAAAA!

Know what I mean?

Could do with a Magician on the job, yh!

 

[bluepoint]

Using telnet, do 'robocfg show' without the quotes, what is port 0 & the lan port you connected the pc's speed connection it reports? Or if you already have RMerlin's beta 3 firmware you can check it from tools.

 

[RMerlin]

Also, make sure you are not using Jumbo Frames anywhere (not on the router nor on your PC). Jumbo Frames can cause serious performance issues if not everything on your network is talking at the right frame size.

 

[Darren M]

Under the Tools tab I have the following:

WAN 1000 Full Duplex
LAN 3 100 Full Duplex

Under the Switch Control tab I have the following:

Enable Jumbo Frame No
Disable HW Accelerator No
Spanning-Tree Protocol Yes

Like I say, I'd changed nothing in the router or on the PC's prior to the loss of speed. When I bypass the router and cable direct to the Modem I get full speed (60 Mb) and very stable using the PC shown on LAN 3. When going through the router LAN ports I get 50% speed and very unstable.

Ah, apart from one thing: QOS had been enabled and then disabled. However, I've defaulted the rouer config settings back to factory state since. So QOS is off, with the default info displayed.

I've just this minute connected a second laptop to the router hard wired on LAN port 1. This laptop is a much better spec, and is only 12 months old. This is shown as below:

LAN 1 100 Half Duplex

A friend of mine has the AC66U. We went through all config settings yesterday, without altering anything. I can confirm that his AC66U is set up exactly the same as my N66U.

Your help is much appreciated guys.

 

[Darren M]

I tried a full reset, uploaded the latest fw version from Asus. Went through the setup process with the minimum config info i.e. just the wireless security settings. This did NOT fix the issue.

I then went back to RMerlin's latest beta fw version, again with the minimum config info. This did NOT fix the issue.

Then I uploaded the config file I'd saved out 2 weeks ago with the QOS settings in, and QOS enabled. This FIXED the issue and I'm now getting full speed once again via a hard wired connection to the N66U.

The only device set up in the QOS section is my Xbox 360 which hasn't been switched on for days.

Obviously a relief, but I have absolutely no idea why this would fix the issue I've been experiencing; anyone else?

Cheers.