Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

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Mayoo
I Plan to Stick Around
Posts: 228

Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

So i am having this weird issue after having gigabit for 1month

I had Modem in Switch mode and my router Asus RT-AC87U in Router mode. After about 4-5hrs, my download speed will go down from 750Mbps to 90Mbps ..

Fix would be simply unplug the RJ45 Cable from the modem side, wait 5sec and plug it back.

First i thought the issue is on the Modem ports, so tried different ports. Same issue

Then i put the modem in router mode and Asus RT-87U in Switch Mode. Same issue

Now i completely removed the router and connected directly and no issues but i am missing my Router Functionalities like DDNS, Remote App etc etc

Anyone seeing  this issue ?

 

I have tried 30/30/30 rest on the route. flashed some other FW, flashed stock firmware and issue is always there. 

 

I never had this issue in the past with Rogers ignite 250u

 

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Datalink
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Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

@Mayoo, fwiw, have a look at the following thread, which is one of the forums at Hardwarezone.com, which is Singapore based:

 

http://forums.hardwarezone.com.sg/internet-bandwidth-networking-clinic-4/%5Bmaylyns-review%5D-asus-r...

 

Just reading thru some of the comments, seems that the 87U is nothing but trouble.  Here's a couple of interesting excerpts:

 

post #930  page 62

Another note for 5GHz ASUS RT-AC87U users.

Please do not include spaces, special characters for the WPA2 password for 5GHz for ASUS RT-AC87U, it will make the 5GHz go bonkers or not operable. Please only use alphanumeric characters.


Post #952    page 64

From RMerlin:  

A lot of disappearing 5 GHz issues were also resolved when people switched to pure alphanumeric WPA keys.

 

 

Personal opinion, if this is new, take it back and exchange it for something else.  If not, best of luck. 

 

Consider any problems with cooling.  Users on that forum have used various objects to elevate the 87U to gain airflow, or used a laptop cooler.  That might be worth trying.  Also note that the 5 Ghz and port 1 are apparently handled by the Quantana chipset, with the 2.4 Ghz and ports 2, 3, and 4 handled by the Broadcom chipset.  That might be food for thought.



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Datalink
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Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

Here is the same complaint:

 

https://www.reddit.com/r/HomeNetworking/comments/3wcmt2/slow_router_asus_rtac87u/

 

Do you use QOS at all?  With gig service and that router, you shouldn't have to.  I run an RT-AC68U and have never used QOS.

 

Here's another interesting read from the Merlin forum which looks very similar:

 

http://www.snbforums.com/threads/high-latency-web-speeds-rt-ac87u.31907/#post-253307

 

First thing I would do is reset the router to full router mode and turn off everything except the firewall and wifi and NAT Acceleration.  Run that and see what happens after a few hours.  This is with the modem running in Bridge mode, acting as a modem only.

 

There may be more out on the internet regarding this, just haven't come across it yet.

 

Have you tried Merlin's firmware on the AC87U , and if so, do you get the same results?



Mayoo
I Plan to Stick Around
Posts: 228

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

Thanks. I have QOS off and tired merlin as well. Will try to go back to pre .380 FW and see if that is going to solve this issue .. thanks .. 

Datalink
Resident Expert
Resident Expert
Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

@Mayoo, fwiw, have a look at the following thread, which is one of the forums at Hardwarezone.com, which is Singapore based:

 

http://forums.hardwarezone.com.sg/internet-bandwidth-networking-clinic-4/%5Bmaylyns-review%5D-asus-r...

 

Just reading thru some of the comments, seems that the 87U is nothing but trouble.  Here's a couple of interesting excerpts:

 

post #930  page 62

Another note for 5GHz ASUS RT-AC87U users.

Please do not include spaces, special characters for the WPA2 password for 5GHz for ASUS RT-AC87U, it will make the 5GHz go bonkers or not operable. Please only use alphanumeric characters.


Post #952    page 64

From RMerlin:  

A lot of disappearing 5 GHz issues were also resolved when people switched to pure alphanumeric WPA keys.

 

 

Personal opinion, if this is new, take it back and exchange it for something else.  If not, best of luck. 

 

Consider any problems with cooling.  Users on that forum have used various objects to elevate the 87U to gain airflow, or used a laptop cooler.  That might be worth trying.  Also note that the 5 Ghz and port 1 are apparently handled by the Quantana chipset, with the 2.4 Ghz and ports 2, 3, and 4 handled by the Broadcom chipset.  That might be food for thought.



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Phonepeople
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Posts: 24

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

I have Asus AC68 u router. I switched to gigabit plan and facing the same issue. 

Before this I was on ignite 100 plan and used to get more than 100mbps speeds on the same router

However, with the new modem CGNM and same router my download speeds have dropped to less than 20. 

But upload speeds are good. 

Tired bridge mode and NAT is off. Not helping. 

Has anyone found a solution yet ?

Thank s 

Datalink
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Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

@Phonepeople, have you resolved the issue with the Gigabit CGNM-3552?  I run the same combination of modem and router, so, perhaps I can assist.  

 

If you haven't resolved this please let us know.  Your the second person to comment on extremely slow speeds on a newly installed CGNM-3552, so that's a little strange.  With correct signal levels, and correct configuration for data rates, you should see the full data rate from the modem.  Now, having said that, it depends on the user devices as to whether or not you actually see the higher data rates.  Fwiw, the maximum rate that I see thru my RT-AC68U is about 840 Mb/s. That's with everything turned off except for the firewall, Trend Micro security and both wifi channels.  

 

First thing I would do is power down or unplug the router from the modem, connect a test pc and run a speedtest at www.speedtest.net using the Toronto Telus or Beanfield server.  http://speedtest.fibrenoire.ca/beta/ also works well for testing the gigabit service.   Confirm that you are seeing the higher data rates.  

 

Unplug the pc and plug the router back in and restart the router.  After its up and running, go through all of the various functions, starting at the upper left hand corner and work your way down thru all of the options and sub-options, disabling anything and everything that you know you are not using.  The one exception to this is the NAT Acceleration, which is found in LAN .... SWITCH CONTROL.  That must stay enabled in order to see the higher data rates.  It should be set to Auto ....CTF (Cut Through Forwarding) is enabled.

 

That is Broadcom's Cut Through Forwarding which routes data through the router without involving the cpu.  Essentially port to port forwarding.  It does work very well and is required for data rates above 100 Mb/s.  However, it can be disabled by any process that requires the CPU to do something with, or to the data, including any form of Traffic Monitoring.  There are a couple of others as well, IPTraffic and possibly QOS.  From what I understand, Adaptive QOS is supposed to work with the NAT Acceleration enabled.  

 

Assuming that you get the router speeds up, keep in mind the status of the NAT Acceleration.  If you see slow data rates after changing any router setting, the NAT Acceleration should be one of the first thing to check in the event that enabling some other function did not produce any warning about disabling the NAT Acceleration.  

 

Here's a coupel of rather interesting lines from the Merlin Forum at snbforums.com:

 

Traffic coming through the forwarded port will bypass CTF, and therefore not be accelerated.

 

The NAT acceleration setting doesn't do anything at all while in AP mode, which is why that setting (along with the rest of that page) aren't accessible in AP mode.

 

Looks like using parental control also kills the NAT Acceleration, which makes sense as the parental control is enacted by a sofware run CPU routine.

 

I don't know if those are only applicable to Merlin's firmware, or if it also applies to the original AsusWRT.  That is something to keep in mind as well.   I'm trying to find the list of functions that kick off CTF (NAT Acceleration), which Merlin has stated somewhere, just have to find it....

 

Please let me know if your having further difficulties. 



Phonepeople
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Posts: 24

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

@Datalink 

I tired everything u suggested but still the download speeds are quite low

With the wifi from the modem i get around 450 - 500 mbps but with asus router the speeds drop to less than 50 now. 

 

 

Datalink
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Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

@Phonepeople when you are testing the router, the modem is in Bridge mode correct?  Dumb question, but, not leaving any stone unturned.....

 

What do you get with a direct connection to the modem when its in Gateway mode, and then after flipping the modem into Bridge mode with the router up in running in full router mode and the same pc or laptop running an ethernet connection to the router?  Is the Nat Acceleration under LAN .... SWITCH CONTROL enabled?

 

Are you using the www.speedtest.net Toronto Telus or Beanfield servers for speed tests?

 

When you connect the router or gigabit port equiped pc or laptop to the modem, the connected port LED on the modem should indicate flashing Amber, meaning that the modem port is connected to a 1 Gb/s device port. 

 

If the port LED is flashing green, then the modem is connected to a 10/100 Mb/s port on the device.  In the case of the RT-AC68U, that has a gigabit port, so, the port LED should be Amber.  

 

If it isn't that indicates that:

 

1.  The ethernet cable isn't making proper contact at either or both ends.  Unplug and replug both cable ends.

2.  The ethernet cable doesn't support 1 Gb/s rates.  Fast Ethernet cables, as they are called don't support 1 Gb/s rates, just 100 Mb/s.  The Fast Ethernet Cables may have been fast at one point in time, but, not any more, and many people have these around the house.

3.  The cable is damaged in some fashion and no longer supports 1 Gb/s rates.  If so, replace the cable.  

 

The results that you obtain from the modem with a direct connection to a 1Gb/s pc will be higher than when you have modem  -  router  -  pc, all with an ethernet connection.  I will see about 840 Mb/s tops, thru the router, and about 440 Mb/s via wifi running 802.11ac.  Thats above the results as listed on the smallnetbuilders web site.  At the present time, I don't believe that there is a consumer router out that will actually reach 1 Gb/s.  Asus will have a monster business class router out one of these days that will reach that and beyond, but thats probably going to be pretty expensive.  



Phonepeople
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Posts: 24

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

Will test it over the weekend and reply. 

THank you for taking time to help sort this issue. 

Datalink
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Posts: 7,221

Re: Gigabit Modem CGNM-3552 and Asus RT-AC87u issues

np.  We'll work thru this one step at a time.  Just be aware, at the end of the day, you might find that your pc's and laptops don't support higher data rates.  I invite you to the discussion that is currently taking place on this topic:

 

http://communityforums.rogers.com/t5/forums/forumtopicpage/board-id/Getting_connected/message-id/362...