Internet Speed Slow When Ethernet and Wireless are Connected

[doggyofone]

I'm at a loss with this problem. I have a Motorola SB6141 modem connected via ethernet cable to an RT-AC66U. The AC66U is running Merlin's 380.57. From the router there are connections to my laptop running Win 10, a telephone modem, powerline adapter and to a switch with 5 connections elsewhere. Everything has been working fine for both wireless devices (phones, laptop, tablet) and ethernet connected. This seemed to change when my wife got a new Laptop.
I was online this AM with good speeds, typically 20-25 mbps on or off the VPN service (VPN runs on the Laptops, not the router). No problems. My wife then started her Dell laptop and goes online and speeds drop off the table for my ethernet and her wireless.
While she's connected I ran Speedtest. The page took 20 seconds to load, Ping 979ms, DL 0.43 mbps, UL 0.09mbps.
She shut down her laptop and I retested - 24ms, DL 24.23mbps and UL 1.90mbps.
We started up her old laptop and it is now very slow as well with my Laptop connected to ethernet.
It seems obvious what is causing the problem, but not why. The Laptop is brand new,
I have reset the modem and reloaded 380.57 - no difference. I have direct connected my Laptop to the modem and speeds are good. We started up her old laptop and it is now very slow as well.
Is there something I should do to diagnose, or is the problem obvious to anyone who can help resolve? Is it possible that 380.57 is causing the problem?

 

[cfbcfb]

I had the same exact configuration up until this week when I got a new router, and I had the same sort of issue. Inexplicable serious slowdowns.

Tried a factory reset to clean up any setting problems? This happened right after I loaded the new merlin f/w. I was in a rush so I loaded the latest stock firmware, did a factory reset and a quick reconfigure. It was fine after that and okay after I installed my new router.

 

[L&LD]

It is possible that the 380.57 firmware is the issue. Try the steps below first and if not successful, try using the RMerlin 378.56_2 firmware or the latest john9527 or hggomes fork (based off of RMerlin's work).

http://www.snbforums.com/threads/no...l-and-manual-configuration.27115/#post-205573

Follow the above link noting the key points below (each time you flash a new or different firmware than what the router is running now).

Use new ssid's after resetting to factory defaults (you can use same password).

Do not use a saved configuration file.

Test whether connecting to the 2.4GHz band or the 5GHz band affects the results positively (make sure you have unique ssid's for both bands to try this).

Test the 'problem' device with a wired connection. Update it's drivers, OS and any network programs it may be using while on the network (wired or wireless).

 

[cfbcfb]

Test the 'problem' device with a wired connection. Update it's drivers, OS and any network programs it may be using while on the network (wired or wireless).

Since I changed to a new router, the only datapoint I can offer is that the performance issue affected both wired and wireless devices. Of the wired, one was windows 10, the other a chromebox. I was still using the original settings from the last firmware update including the ssid/passwords. The action was flaky, as though the connection was flooded or dropping in and out. I put the latest stock asus firmware on, factory reset, same ssid/password, all was well.

 

[doggyofone]

Thanks Guys. I've followed L&LD instructions and am running on 380.57. I will keep an eye on it and if problems will try the other firmware options. I will also get back to you with results.

 

[doggyofone]

So far, so good guys. No issues this AM. 20+ mbps on both Laptops, ethernet and wireless.
FYI, while internet problems were on the go yesterday, I did a speedtest on my Tablet running CM12.1. While the Windows 10 devices were struggling the Android device was running at over 20 mbps download speeds.
Thanks for your excellent help and advice. I'll continue to do this "pre-cleaning" whenever I flash. Also, thanks for the links to the Merlin forks. I'll experiment with those when I get a chance.

 

[ozzed]

I'm at a loss with this problem. I have a Motorola SB6141 modem connected via ethernet cable to an RT-AC66U. The AC66U is running Merlin's 380.57. From the router there are connections to my laptop running Win 10, a telephone modem, powerline adapter and to a switch with 5 connections elsewhere. Everything has been working fine for both wireless devices (phones, laptop, tablet) and ethernet connected. This seemed to change when my wife got a new Laptop.
I was online this AM with good speeds, typically 20-25 mbps on or off the VPN service (VPN runs on the Laptops, not the router). No problems. My wife then started her Dell laptop and goes online and speeds drop off the table for my ethernet and her wireless.
While she's connected I ran Speedtest. The page took 20 seconds to load, Ping 979ms, DL 0.43 mbps, UL 0.09mbps.
She shut down her laptop and I retested - 24ms, DL 24.23mbps and UL 1.90mbps.
We started up her old laptop and it is now very slow as well with my Laptop connected to ethernet.
It seems obvious what is causing the problem, but not why. The Laptop is brand new,
I have reset the modem and reloaded 380.57 - no difference. I have direct connected my Laptop to the modem and speeds are good. We started up her old laptop and it is now very slow as well.
Is there something I should do to diagnose, or is the problem obvious to anyone who can help resolve? Is it possible that 380.57 is causing the problem?

One thing to consider is that LAN-1 is wired to the 5ghz-radio instead of the main-SoC, which can cause issues. Avoid connecting anything to LAN-port 1 if you can and use other ports instead. I was having issues with 5Ghz and using a port different from LAN-1 solved it.