weird interference to wirless rounter

[edwpang]

I have been following SNB for quite some time, and I remember I once registered with another email which I forgot, but I rarely post in the forum. Today I really need to share my experience...

Starting from a few days ago, my good old Linksys WRT 54GL with DD-WRT firmware suddenly stopped accepting wireless client, even within 3-5 feet. The signal was very strong, but just wouldn't pass the "obtaining IP address" phrase. A whole house of wireless devices just stopped working. I tried everything I counld think of: changing channel, changing wireless encryption, and resetting the router. All these just doesn't work. I though the router wireless module was dead. So I bought online a new Asus n56u router, and set it up today. It's just a little better! I can connect to the 2.4G band, but it's very slow and unstable! 5G is ok. So a new round of experiments, then I searched online, and actually found out in SNB, the best firmware is 3.0.0.4.206, but it's still the same. Eventually, my PC BSODed(1st time since I installed Win8 half a year ago), the wireless speed miraculously increased to 20mbps in the same room, and 8-9mbps at the opposite side of my house. After the PC fully boot up, the slowness came back, so I just disconnect it, speed go back to normal again. For final solution, I connect the wired LAN cable though a switch to the router, everything is OK now!

 

[coxhaus]

Using a switch plugged into the router is the preferred way to connect devices to the network. If you want to check on the problem more, I would check the CPU usage while it is connected to the router. It may be maxing out the router CPU.

 

[edwpang]

I think my issue is caused the interference injected through the lan cable into the router. Sometimes, the speaker connected to my PC gives out a very pitch sound, which probably also comes out from the PC. Another thing is the 5G band is NOT affected, so I don't think it's router high CPU usage.

Edit: from Wikipedia:
Electromagnetic interference (or EMI, also called radio-frequency interference or RFI when in high frequency or radio frequency) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.

 

[coxhaus]

You need to trace down your wires. Make sure they are not lying parallel to fluorescence lights or high power cables. If you have to cross lights or power cables then cross at 90 degrees.

 

[Mike_G_D]

Is the PC that you mentioned in your first post (the one that BSOD'ed whereupon the wireless connections to your other devices improved) using a wired or wireless LAN connection? I wasn't clear on that from reading your posts. If it is wired and not using wireless then does it have a built in wifi card that might be inadvertently activated and causing problems (some software might do this and/or updates, etc.)? If it is wired you need to make sure that the wifi adapter/card, if present, is disabled. Also, does that PC use or have a Bluetooth adapter built in? If so, that too could be activating and screwing up the 2.4GHz band. So make sure ALL wireless cards/adapters in the PC (the one that seems to mess up your 2.4GHz wifi band), if present, are OFF completely.

Even if the "noisy" PC is using wireless normally it may be that its wireless card went south either due to a bad driver update or a hardware failure. Or, again, another competing wireless card (e.g. Bluetooth) got activated inadvertently.

Another thing to look at is USB 3.0 adapters and connections as these can cause significant interference on the 2.4GHz band if not shielded properly.

You mention that the 5GHz band is ok and does not suffer from this problem so it seems to me that it is radio related and not related to higher level network issues.

-Mike