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Old 08-01-2020, 01:43 PM   #1
business_kid
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Pi 4 slow wifi?


I've been having Slow Wifi issues on my RazPi on 2.4Ghz. This is local wifi in a small house. It's slower than anything else in my place atm. Things I've done include
  1. Trying an update of the firmware binary brcmfmac43455-sdio.bin to the latest from the git of the kernel firmware. No help.
  2. I noticed the firmware txt files were config files, assigning values to labels. There was one for the Rpi-3, one for the Rpi-4, and another for some weird name. The Debian stuff I was using just had brcmfmac43455-sdio.txt. I diffed that with the RazPi-4 one in the kernel git, and they differed. So I copied the RPi-4 file from the kernel git to my firmware dir as brcmfmac-sdio.txt. That may have gotten me a few % increase.
  3. Researched the hardware, which was interesting. Cypress start their chip numbers with CY, and Broadcom with BCM. There was a Broadcom manufactured IC BCM43454 & BCM43456; But the only BCM43455 was manufactured by Cypress. The brcmfmac43455 runs the RazPi-4 wifi, but I presume it's an IP core (or a chunk of an ASIC design) in the APU, the BCM2711 SoC. The key factor here is that they're unlikely to have tested the hardware sensitivity in the BCM2711 core like they tested the one in silicon.
  4. Researched my local problem. One of the things I tried was 'iwlist wlan0 scan |grep -c Channel' . The RazPi counted 20. As fast as I could get upstairs I tried it on the Laptop, there was 36. With 'iwlist wlan0 scan |grep -A2 Channel,' my Laptop (with an ath9k wifi) was spotting channels at ≥-92dBm, or Quality 17/70. I saw basically nothing below 40/70 on the RazPi, so the sensitivity is low. That means channels it doesn't know about could be interfering with it. That could confuse things.

I'm running out of clever things to do here that yield any information. Has anyone any ideas for me? I seem to have taken it about as far as I can, and although my Pi was bought as a media server, It won't download fast enough to do that.
 
Old 08-01-2020, 03:44 PM   #2
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Hardware's cheap, do you have another one you could try? E.g: https://www.ign.com/articles/best-usb-wifi-adapter &c...
 
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Old 08-02-2020, 03:19 AM   #3
Exaga
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Quote:
Originally Posted by business_kid View Post
I'm running out of clever things to do here that yield any information. Has anyone any ideas for me? I seem to have taken it about as far as I can, and although my Pi was bought as a media server, It won't download fast enough to do that.
We have previously touched upon the reasons why I don't think it's a good idea to use the on-board Raspberry Pi wireless device. Unless your RPi is located approx. 1 metre from your router then in my experience it's less troublesome to use a USB wireless adapter (or stick to using an Ethernet connection when possible). In fact, it would be a good idea, and prudent for you to do that anyway in order to save yourself some time, effort, and headaches.

Quote:
Originally Posted by jamison20000e View Post
Hardware's cheap, do you have another one you could try? E.g: https://www.ign.com/articles/best-usb-wifi-adapter &c...
Excellent, sensible, and logical advice.

I have half a dozen of these USB wireless network adapters laying around for testing and such. They're quite handy for other things than just ARM devices. From my experience with Slackware ARM on the Raspberry Pis, I've found the most reliable and trouble-free choice (and one of the most affordable) is the Ralink RT5370. It's not dual-band or USB3 but that option is always there for users with more ambitious requirements, and bigger wallets, provided that the drivers are available.
 
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Old 08-02-2020, 04:54 AM   #4
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I must say I didn't have any trouble with the wifi until recently. There's a couple of people about that have gone over to 5Ghz. Sadly, I'm inclined to agree. It seems a number of the local routers are on 'Autochannel' so 2.4Ghz is unpredictable.

I'm going to mark this solved. The solution is that Broadcom wifi is crap. As a hardware guy, I regard faulty hardware as a last resort diagnosis, but it sadly seems to apply here. I saw one 'Quality' signal at 27/70 (-82dBm) but I immediately scanned again and it wasn't there. That's not good enough.

I'll need a usb 3.0 wifi dongle with 5Ghz, not the cheapo ones. I'll go shopping.
 
Old 08-02-2020, 01:31 PM   #5
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There are a number of additional factors involved besides the chip set and the firmware of your device. Are you using the same channel as the majority of other access points in wireless range? Do you have signal interference due to the physical location of your hardware? How many clients are there on your wireless access point and do you have quality of service (QoS) enabled? What else do you have running on your Pi or on your network? Is anything poorly configured on your router or do you need to update the firmware of your router?

I've said it before, but... I have had great success with the pi 3b as a wireless router using hostapd to serve WiFi to all types of devices on my network. One of our smart tvs is in a room that doesn't have an Ethernet connection and it works well on the wireless connection. I typically have a mix of 14 devices (phones, laptops, tablets, printers, tv, even the sprinkler system) on my connection and do not experience any of what you are reporting.
 
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Old 08-02-2020, 02:58 PM   #6
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@business_kid

As per jamison20000e's advice, you should opt for an external adapter. It's not only the HW, but also the weird antenna design that was first tested/implemented on the Pi Zero W boards:
https://magpi.raspberrypi.org/articl...antenna-design
At least on those boards you still got the possibility to solder an antenna connector and use an external antenna:
https://www.raspberrypi.org/forums/v...c.php?t=176249
https://www.briandorey.com/post/rasp...al-antenna-mod

Not sure if you can do that on the Pi 4 board, still, there are successful hacks for Pi 3:
https://hackaday.com/2016/03/18/hack...a-for-more-db/

Then, there's a design flaw in the Pi 4, excessive noise interfering with the 2.4 GHz channels:
https://www.tomshardware.com/news/ra...fi-not-working

And as you've already noticed, there's chaos in the 2.4GHz band, as all the routers are using automatic channel selection algorithms by default and trying to use a non-overlapping channel, of which there are only 3 - 1,6,11 (that's on HT20 (20MHz bandwidth)).
https://en.wikipedia.org/wiki/Wifi_interference#Wi-Fi
https://en.wikipedia.org/wiki/File:N...GHzWLAN-en.svg

... that's only half the story. With the introduction of the 2.4GHz extension 80211.n, 40MHz wide channels "HT40" were allowed/implemented and used (enabled) based on survey and availability. But most of the cheap Chinese Access Points had them enabled by default in their firmware, in an abusive way, occupying (polluting) the 2.4MHz spectrum.
Discussion:
https://forum.openwrt.org/t/40mhz-80...mhz-wide/19547

For properly using the 2.4GHz band you need some good equipment nowadays - HW & antenna. On the other side, the 5GHz band is still OK, wider channels and not that much noise, as most of the "common" routers are not supporting it, but the coverage is lower (50%-75% compared to 2.4GHz).

Last edited by abga; 08-02-2020 at 03:25 PM. Reason: HT20
 
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Old 08-03-2020, 05:02 AM   #7
business_kid
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@mralk: I think the figures speak for themselves
  • Mobile phone on wifi away from router 49 Mbps download
  • Laptop not badly placed for router - 35-40Mbps d/l
  • Razpi 4 well placed from router - ≤7Mbps, dropping badly at crowded times.

I get a 100Mbps connection from Glass fibre coming via dsl to the router at about 60Mbps. The RazPi is well placed vs the other two. The the last thing I want to do is experiment on this. I'm now seeing if I can get a 5Ghz router from my isp, and I have another thread open on the Ralink chips to see what support is like. Instead of using unsupported Realtek stuff, now these usb adapters w/5G all have the Ralink 5370. I can disable the 2.4Ghz AP, put in a 5Ghz AP. I mightn't even need anything for the Pi.

agba, thank you for the well researched post. Thanks for the links. My days of hacking hardware are over, it seems. Phone companies here are inclined to buy, install, and support decent modem/routers. It's interesting what you say on Pi 4 wifi issues. I think the antenna goes up the side of the pcb, but there's still polarisation & one or two other issues to eliminate.
 
Old 08-03-2020, 05:14 AM   #8
pan64
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I do not really know if it was valid for RPi4 too, but bluetooth and wifi could not work well together on earlier devices (like RPi3). Also (unfortunately) I bought a nice metal box for my RPi3 which blocked both (bluetooth and wifi). It may also depend on the power supply of PRi. Otherwise buying a good external wifi stick (with a powered usb hub) is probably a quick and reliable solution.
 
Old 08-03-2020, 10:22 AM   #9
business_kid
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My wife says: "There's no bigger fool than a clever fool." I must confess…

A relevant item of information That wasn't disclosed is that of late, I've been using a Flirc case.They've stuck a black covering covering on the 'heatsink' side, so it looks quite like the rubber side, but I thought I knew the difference. I checked that the Flirc case doesn't affect wifi reception. The guys at Flirc assure folks that it doesn't; but if it's earthed, the signal probably would be affected. Whether the case is in fact earthed depends on imponderables, but for CE approval in Europe it would have to be.

So, despite my limitations, I started messing. Before digital TV, (here in early 2000s) the science of making distant signals into usable TV pictures was very highly developed in Ireland. I know the ropes myself. So starting with 15Mbps d/l on a very quiet and dry afternoon, I got the download up to ~25Mbps by pointing (as I thought) the rubber side of the case directly at the wifi router, and polarising it correctly. Back in the Analogue TV days, they used list the polarization of TV channels, as looking for a vertically polarized signal with a horizontally polarized aerial yields poor results.

Anyhow, to multiply my embarrassment, I turned the case around so the 'metal' pointed at the wifi. I expected it to slow, but I got up to 30Mbps! For this house, 30Mbps is good enough. It's certainly enough to stream hdmi @60Hz.
 
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Old 08-04-2020, 04:54 AM   #10
Exaga
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Quote:
Originally Posted by mralk3 View Post
I've said it before, but... I have had great success with the pi 3b as a wireless router using hostapd to serve WiFi to all types of devices on my network. One of our smart tvs is in a room that doesn't have an Ethernet connection and it works well on the wireless connection. I typically have a mix of 14 devices (phones, laptops, tablets, printers, tv, even the sprinkler system) on my connection and do not experience any of what you are reporting.
Sounds great!

I have a dual-band router (2.4GHz and 5GHz) and I generally only have 2-3 wireless devices connecting to it; iPhone, laptop, tablet. Any devices that are capable of using the 5GHz band I'll connect to it. Otherwise it's the 2.4GHz. I'm not a passionate advocate of wireless Internet technology and much prefer to keep my data confined to Ethernet cables when at all possible.

With the RPi3 the on-board wireless for me is/was very unreliable. I have tried all sorts of tricks and ideas to try and overcome the constant wireless connection drop-outs, etc. including a RPi tin-foil hat (and I'm not joking!). Nothing seems to be 100% successful. The thing that makes the biggest difference on my setup is capping the data transfer speed to approx. 1Mb/s and then it stays connected for longer periods without dropping, but it will always eventually drop-out. The RPi3 on-board wireless also behaves itself a little better if the device is <1 metre from my router but will still lose connection once I start to transfer large amounts of data - only maybe not quite as often. When using a USB wireless network adapter with the RPi3 none of these issues are apparent for me. This is why, whenever I need to use wireless Internet with the RPis, I just plug in a USB wireless network adapter and configure it rather than waste time with the on-board shizzle.

I've recently ordered a RTL8812BU-based wireless network adapter which is USB3, 2.4GHz and 5GHz dual-band, and boasts a 1200Mbps data transfer rate. So I'm interested to use this with Slackware ARM on the RPi4 and play around with it. Only problem I can foresee is that RealTek don't have any Linux drivers available for download on their official site but there seems to be some RTL8812BU support on GitHub for various kernels. I'm pretty confident that Slackware ARM will be accommodating towards this chipset anyway, and if not then I'm damned sure some jiggery-pokery will make it happen.
 
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Old 08-04-2020, 07:21 AM   #11
business_kid
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After my experience, it seems the sensitivity of the 43455 is suspect, and it handles interference poorly.

Any Pi case that isn't metal probably has a big fan in the way. Polarizing the board correctly (parallel to the aerial) always helps. Orienting the aerial to get a good direct path or just trying it different ways is worth a shot. It's trivial to do that sort of thing - less trivial for me since my stroke. My download speed held up pretty well when the crowds came home; but yesterday was a bank holiday here, so I'd expect heavier streaming later in the week.

The 8188BU is not currently supported, but it will get added to the rtlwifi kernel module in time. It seems Realtek never got a programmer accepted to write kernel code, but things are moving somehow now. Neither, for that matter, did Ralink/Mediatek. Things don't seem to be moving there. Their one driver up there is from 2012, and uses a RHEL 2.6.1 kernel as a base. IIRC, there's been a reordering of kernel headers since then, so compiles are going to be messy.

Last edited by business_kid; 08-04-2020 at 08:29 AM. Reason: I wrote complete gibberish. I knew what I was talking about, but…
 
  


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