WiFi: going from good to great is very hard

WiFi: going from good to great is very hard


So i have a moderately complex home network. 5 access points lurk around, hard wired to each other. 3 of them speak 2.4+5, and 2 of them speak only 2.4GHz.

Saturday one of them came up for replacement. And since it covers a small area and is the main north-south gateway for my house, I chose to go for a device that has more RAM/CPU, and more average WiFi capabilities. And thus the rabbit hole of rebalancing occurs.

For those who don't know, the 5-GHz band has some limitations. First, in most regulatory domains (countries usually), there is a requirement that some of the frequencies do 'DFS' which is designed to detect weather radar systems (in case you are near an airport). I'm not, but I'm not allowed to disable DFS. Also, each channel as a different peak power allowed, as well as a different width. You can read about WiFi channels for you country here, and i've reproduced the first few columns below.

So as you can see, you want to use channel 42, 50, 155 from a width standpoint. Channel 155 allows 30dBm of power whereas 42 only allows 17, and 50 allows 24. But, that DFS column, you really want to avoid this if you can. It  turns out that false positives happen here, and, when they do, your router switches to another frequency and drops power.

So you now have a choice. Either not use the VHT80 mode and skip the DFS channels. Or use the VHT80 mode and have overlap (interference). Or use VHT80 and DFS and hope they don't move. Well, I tried that latter, and now my WiFi analyzer is telling me (as is my log file) that weather radar was detected. Boo. It only looks like a lot of channels. Basically there are only 2 non-DFS blocks, and only one of these is high power. And, each uses the whole block if you use VHT80.

Since I'm seeing false positives on the DFS detection, my 3rd 5GHz band is jumping ship and moving (and jumping on top of one of the other 2 non DFS bands which i've used the whole width on). [side note, you can see what your router wants to do by running 'iw reg get' on it).

The 2.4GHz band I managed more simply. There are only 3 non-overlapping channels (1,6,11) for 2.4GHz. I have 5 AP (plus 1 that is there for my alarm system I guess, plus 3 from my neighbours that broadcast @ high power). This gives 9 things vieing for the 2.4GHz 3 channel. So i've tuned my power down, directed the antenna a bit, and well, not a lot uses the 2.4GHz band for clients, just some of the devices like thermostats, older chromecasts, etc, so I don't care too much.

So, anyone care to comment on how they solved this dilemma? Is ignorance bliss and I should just ignore? I can kind of see now why the hackers disable DFS and power limitations, but that would be wrong.

Channel Freq Freq-Range Bandwidth USA Canada
36 5180 5170-5190 20 Yes Indoors
38 5190 5170-5210 40 Yes Indoors
40 5200 5190-5210 20 Yes Indoors
42 5210 5170-5250 80 Yes Indoors
44 5220 5210-5230 20 Yes Indoors
46 5230 5210-5250 40 Yes Indoors
48 5240 5230-5250 20 Yes Indoors
50 5250 5170-5330 160 DFS DFS
52 5260 5250-5270 20 DFS DFS
54 5270 5250-5290 40 DFS DFS
56 5280 5270-5290 20 DFS DFS
58 5290 5250-5330 80 DFS DFS
60 5300 5290-5310 20 DFS DFS
62 5310 5290-5330 40 DFS DFS
64 5320 5310-5330 20 DFS DFS
102 5510 5490-5530 40 DFS DFS
104 5520 5510-5530 20 DFS DFS
106 5530 5490-5570 80 DFS DFS
108 5540 5530-5550 20 DFS DFS
110 5550 5530-5570 40 DFS DFS
112 5560 5550-5570 20 DFS DFS
114 5570 5490-5650 160 DFS No
116 5580 5570-5590 20 DFS DFS
118 5590 5570-5610 40 DFS No
120 5600 5590-5610 20 DFS No
122 5610 5570-5650 80 DFS No
124 5620 5610-5630 20 DFS No
126 5630 5610-5650 40 DFS No
128 5640 5630-5650 20 DFS No
132 5660 5650-5670 20 DFS DFS
134 5670 5650-5690 40 DFS DFS
136 5680 5670-5690 20 DFS DFS
138 5690 5650-5730 80 DFS DFS
140 5700 5690-5710 20 DFS DFS
142 5710 5690-5730 40 DFS DFS
144 5720 5710-5730 20 DFS DFS
149 5745 5735-5755 20 Yes Yes
151 5755 5735-5775 40 Yes Yes
153 5765 5755-5775 20 Yes Yes
155 5775 5735-5815 80 Yes Yes
157 5785 5775-5795 20 Yes Yes
159 5795 5775-5815 40 Yes Yes
161 5805 5795-5815 20 Yes Yes
165 5825 5815-5835 20 Yes Yes

 

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