(Very) Poor Wifi on Pi400 [Solved]

[Inglenook]

I have a Pi 400 with Raspbian Buster installed. I’ve attached a Samsung EVO 840 SSD via a USB 3.0/SATA cable, which works well. I plan to have the Pi 400 as a file server. I have the Samba server installed and running. I am hoping to use WiFi as the network for the Pi 400 – I have both 2.4G and 5G networks in the house and these work well with all my existing equipment.

I am able to configure and use both 2.4G and 5G Wifi on the Pi 400 and both give stable networks. Samba works with various clients including MacOS, Windows 10, Android.

Unfortunately, the performance of the Pi 400 over Wifi is very poor. Here are results from iPerf3:

Client Server Network Speed
Mac. Pi 400. 5G. 9.02Mbps
Android. Pi 400. 5G. 8.89Mbps
Android. Mac. 5G. 128Mbps
Mac. Pi 400. 2.4G. 12.9Mbps

So, the network is capable of giving something like 10x higher data rate than I am getting with the Pi 400. I know it is not a location issue since all the systems involved are within a couple of feet of each other and moving them makes little difference.

I have run wavemon to get stats on the Pi 400 WiFi and get output similar to the attached screenshot:



Any ideas about why the Pi 400 WiFi is so poor?

Mike.

[epoch1970]

It's not "the network". It's the capabilities of the AP and then of each client individually.
The Pi has less and smaller antennae than other machines, it is slower.
https://serverfault.com/questions/81138 ... cess-point

[fanoush]

I’ve attached a Samsung EVO 840 SSD via a USB 3.0/SATA cable
...
Any ideas about why the Pi 400 WiFi is so poor?

There is known interference issue with USB 3.0 and 2.4GHz wifi.
https://www.intel.com/content/www/us/en ... paper.html
so could be your SSD, but that should not happen with 5GHz wifi (?).

[Inglenook]

I can accept that the Pi 400 may have smaller WiFi antenna than some other devices (although the Android mobile phone ones are not all that big, as I understand it). However, I would expect the limitations imposed by the Pi 400 hardware to reveal themselves in some way. Plus, I get the impression from other posts on the forums relating to Pi 400 that other folk are getting better WiFi performance than I am experiencing. <10Mbps seems on the low side for 5G WiFi.

I was hoping that someone knowledgeable about the Pi 400 WiFi could see anything amiss in terms of the wavemon data I attached in my previous post, or suggest other tests I could run.

Many thanks,

Mike.

[mahjongg]

One reason for bad radio communication (WiFi) is disrupted supply voltage, (which directly influences transmission and reception of radio signals) so are you using a suitable supply, and a suitable supply cable?

another reason could be interference from USB or HDMI cables, that are "leaking" frequencies that interfere with the WiFi frequencies.

[sup]

I needed to apply new firmware to get decent wifi speed and stability, see details in the first post linked from this thread: viewtopic.php?f=36&t=291825

But position of the pi regarding the router brings enormous differences - easilly drop from 75mbit to 30 mbit over five metres and twenty cm of concrete - something my laptop handles with no real issues.

[TheTurnipKing]

I've been wondering if the shielding might have an effect, though the wifi chipset and antenna seem to be at the rear of the system and it doesn't seem like it should be all that close. It's not an enclosed can, after all, just a flat plane.

Edit:: That said, I just knackered the keyboard connector taking the heatsink off, but the WiFi does seem to be consistent and reliable now.

At least, I was able to successfully pull a movie off my NAS, which would consistently time out at a random point just yesterday evening.

Whether it's down to removing the heatsink or something else utterly arbitrary I haven't taken into account, I have no idea.

I should, I suppose, next put it back in and see if the behaviour reoccurs.

edit: and it's back in, and the wifi seems about the same as it was with it out, now. So presumably it was something else.

[Inglenook]

Thanks for the discussion and the suggestions. I am going to try out some changes, starting with the firmware updates and then changing the HDMI settings. I will also see what happens if the USB attached SSD is detached, in case that is causing any interference.

I think I can discount any problems with the supply voltage - I bought the Pi 400 Kit and so I am using the approved Pi power supply with USB-C connector for the Pi 400.

I have tried out various combinations of network connections, both to the Pi 400 and to my other systems, the Mac laptop in particular. I can connect the Pi 400 over a 1Gbps Ethernet connection - and with the Mac also attached on a 1Gbps Ethernet, I can get iPerf3 figures up to 941Mbps, which is pretty well maxing out the network. Even where the Mac is connected over 5G WiFi & the Pi 400 over 1Gbps Ethernet, I can get 356Mbps. So I know I need to concentrate on the Pi 400 WiFi.

Regarding the heatsink, if that were the real problem, then everyone would be experiencing poor WiFi speeds - and that does not seem to be the case, at least from my reading of the forums here.

[teamtiem]

A server should be a ethernet connection. The Pi 400 is to use as desktop PC. Not as server. Better buy a RPI 4 2 GB for the server and put it near the router with a ethernet connection. 2 GB is far enough for a server.

[Inglenook]

The use I plan to make of the Pi 400 does not excuse such poor performance of the WiFi - and the advantage of a Pi 400 and 4Gb RAM is that the single machine can perform multiple functions simultaneously.

I have now checked that the USB 3.0 attached SSD has no effect on the WiFi performance.

I have also checked that HDMI signals do not seem to interfere with the WiFi - I have changed to much lower screen resolution and I have also detached the monitor. Neither has any effect on the WiFi.

Now for the updated drivers...

Mike.

[DougieLawson]

What are the walls made of? Have you looked at WiFi repeaters or WiFi mesh?

Does it work better if you switch to 5GHz?

[Inglenook]

Dougie,

I am in a brick house, but I have organized my WiFi to deal with that - I have a lot of other equipment using the WiFi without problems.

I am mostly using 5G WiFi although it does not seem to make much difference for the Pi 400 from using 2.4G.

The real issue is that the Pi 400 WiFi is *much* worse than any other of the devices I'm using, in exactly the same locations where I'm using the other devices. That includes "small" devices like Android phones. In fact I use a WiFi signal strength app on my Android phone to check out the signal strength of the WiFi around the house, both for 2.4G and 5G, since it is so portable.

The Pi 400 WiFi is at least 10 times slower than other equipment in the same locations. I think this must be something to do with the configuration of my Pi 400, since I see discussions on the forums here where other folk are clearly getting much higher WiFi speeds on their Pi 400s. My Pi 400 is a pretty "vanilla" install with Raspbian - I've not tweaked things as yet. The driver upgrade will be the first significant change.

Yours, Mike.

[Inglenook]

OK, so I switched to the BCM43456 (Pi 400) WiFi drivers, as described in the thread
viewtopic.php?f=117&t=291688

The effect is immediate and major.

With a MacBook as client and the Pi 400 as server, both using 5G Wifi and basically sitting next to each other on a desktop, iPerf3 numbers change as follows:

Old drivers: 9.02Mbps
New drivers: 148Mbps

The new figures are definitely more like the speeds I was expecting and are acceptable for my purposes. I'll take a 15x improvement any day!

So the problem was really with the old WiFi drivers in Raspbian. I suggest that the new drivers need to become part of the standard O/S install for Pi 400 ASAP.

[DougieLawson]

I am in a brick house, but I have organized my WiFi to deal with that - I have a lot of other equipment using the WiFi without problems.

At least it's not metal coated insulation which isn't good.

I am mostly using 5G WiFi although it does not seem to make much difference for the Pi 400 from using 2.4G.

5GHz has a shorter range than 2.4GHz but a larger bandwidth.