2.4 GHz Interference to WiFi

[VK2CSW]

Hi All,

Amongst all of the trials and tribulations of trying to get NBNCo to come and look at the interference their equipment is causing a new issue appeared.

The Ping times would blow out, Down and Upload speeds would drop into the sub 0.5 Mbps range and connections would start to time out.  With everything else RSP/NBN related this issue caused much frustration and swearing. 

The WiFi sniffer showed that the signal strength was OK, few overlapping other services, so all good it seemed.  I ran a 20m ethernet cable to the router and presto - performance was back.  Unplugged and down it went again.

After much searching and hair pulling (okay that's a lie - there's none left   ) it turns out that the wireless keyboard was wiping out the 2.4 GHz spectrum.  As soon as the batteries came out of it the WiFi started to play nicely.  Back to a wired keyboard for now.

So for future reference does anyone know of a way of looking at the 2.4 and 5 GHz spectrum for just such interference - without spending thousands on a fancy Spec An?

Would any of the SDR type dongles get to those bands and what software would be needed?

[VK4ADC]

The first step is to alter the channel that your router works on. If it is the low end, alter it to the top end. Go into the router configuration screens and try some changes. I don't get interaction between my wireless keyboards, mice or other so careful channel selection can solve it.

One of the other common wireless networking "interrupters" is your microwave oven. It's high power and can be anywhere in or around the 2.4GHz spectrum !!! Don't tell the missus that she can't warm her coffee or cook your dinner - she will not be amused.

[VK2CSW]

Hey Doug,

One of the first diagnostic steps was to move the WiFi channels - I was thinking that overlapping services may have been the cause. It made no difference.

The keyboard is a $15 Officeworks job, that even included a mouse so I got what I paid for - truthfully it has lasted about 18 months so no great loss to bin it.

I might try an experiment or two before is gets binned but I cant face any more stress

[VK3ALB]

Interesting problem.

I have similar issues but for me the keyboard/mouse are the victims. Certainly, moving the channels about on the router and dropping the TX power to the lowest possible level has made a big improvement although every now and then I still have trouble.

Most low(ish) cost SDR stop at around 2.1 GHz but perhaps someone out there knows of one suitable for monitoring the WiFi band.

[VK4AN]

Plenty of apps out there that run on a notebook if you have one, ie Netspot. One of the biggest issues with WiFi is folk running them at max power, which causes all sorts of issues in 2.4 when you only have three discrete channels. Where possible, use 5.8 rather than 2.4.

[VK3RX]

One of the biggest issues with WiFi is folk running them at max power

I've always wound the power back in our WiFi modems to the minimum extent necessary. No point broadcasting to the surrounding houses and passers by.

The vast majority of the population don't realise running max power is unnecessary and has its issues, including security.

[VK2CSW]

Plenty of apps out there that run on a notebook if you have one, ie Netspot. One of the biggest issues with WiFi is folk running them at max power, which causes all sorts of issues in 2.4 when you only have three discrete channels. Where possible, use 5.8 rather than 2.4.

Had a look at netspot, well the demo one and it looks like a wifi protocol sniffer rather than something that will detect rogue (non-wifi) signals.

I would love to use the 5 GHz connection from the router but none of my end point hardware, apart from my phone, is endowed with 5 GHz capability.  Might pick a USB wireless NIC and have a play.

Spent a bit of time in the ceiling this afternoon, roughing in some Cat5 cable that will replace the 40 year old PMG cable currently in use.  When I opened the cap of the Gas Arrestor on the barge board, low and behold, it was a mess of added wires and scotchloks.  The Telecom Liney in me uttered a few oaths and I felt compelled to tidy up the abomination.  None of that was there before the NBN install.

The connection has been stable since, but it is too early to tell, I'll know by morning if it has made any difference.  I've also put a VDSL central filter into the cable that connects the FTTC box into the PMG cabling.  Ordered the filter from Wagners on Saturday afternoon, was on my doorstep Tuesday before 10.00 AM.

[VK2CSW]

Well the scotchlok removal has helped stability a little.

The Cat5 cable is roughed in from bargeboard to outlet. My Krone tools is at work, so a friend who is an ACMA cabler is dropping by for a beer this afternoon with his.

Once that is done I will retest for all of the myriad of NBN issues, especially:
a. DPU or NDC causing HF RFI;
b. DPU locking up.
c. WiFi interference issues.

Frankly once it is recabled, I am the whim of NBNCo as to whether it will ever get fixed.

[VK2CSW]

Well, some results are in.

The new cabling has made the RFI worse. Trying, again, to get NBN to attend.  I have also filed an ACMA Interference Report.

The DPU/NDC lock up issue appears to have improved.  I say appears because we had several power outages today which reset the units, so I am not sure if it really is fixed or if the restarts are masking the issue.

The WiFi interference looks like is may be a known issue with the cheap-as-chips Sagemcom router supplied by Optus.  Whingepool er Whirlpool seem to be very critical of it. In light of this I think I'll run a test with a different router, the trouble is if it proves to be the router it then becomes a hassle as the 'landline' is fed from the router and I am not sure if it is possible to replace the router and reconfigure it to run the phone.