TLDR Summary: If you have slow speeds or are unable to connect to WiFi Wlan 2.4Ghz and you are using the HDMI output.
Try changing the resolution and/or the refresh rate for the monitor.
Try a different HDMI cable
Try changing the WiFi channel on the access point.
See the article from 2019: https://hackaday.com/2019/11/28/raspber ... own-wifi/
The comments hints the issue was ‘fixed’ but offers no link.
Perhaps this is related to the older B0 version of the SOC.
https://www.jeffgeerling.com/blog/2021/ ... 0-stepping
A story of 2 PI’s.
Purchased 2 PI 4B 4gb from the same seller in December 2023 second hand.
Both boards passed extended stressberry and video playback testing.
It was when checking WIFI speed that the fun started.
Let's call them:
slowpi = has issues with WIFI speed at 2.4 ghz
and goodpi = no issues
For both units 5ghz WiFi speed is unaffected.
Similarities between the units:
Hardware core speed 1.8ghz
EEPROM updated to: VL805
Differences between the units:
Slowpi:
SOC is the B0 version
Bootloader: “Tue Feb 16 01:23:36 PM UTC 2021 (1613481816)”
Note: that after upgrading the bootloader to the latest on slowpi made no difference in test results. Updated to: “Wed Jan 11 05:40:52 PM UTC 2023 (1673458852)”
Goodpi:
SOC is the newer C0 version
Bootloader: “Thu Apr 29 04:11:25 PM UTC 2021 (1619712685)”
I did not upgrade this yet.
I only found out about B0 and C0 SOC versions after all testing. I think this difference in boards is the most probable cause of slowpi. Perhaps they added more HDMI shielding when they updated the SOC but I can’t find anything that indicates it. The other possibility is the B0 Slowpi has a defect.
Test Setup:
Bookworm updated to 2024-01
Testing with iperf3 to a server. The server is connected to the WiFi Access Point via ethernet at 1gbs
Canakit Raspberry PI 4B power supply (from my other 4B Kit)
Cable Matters HDMI to VGA adapter
VGA Monitor: Dell 1907FPt - an old 19" Fullscreen (1280 x 1024)
I also tested with a Dell G3223Q 4K monitor and different cable separately. See below.
Screen resolution and refresh rate was changed using the Screen Configuration in the GUI.
iperf3 test results in the chart were run for 30 seconds client PI to server (upload).
Tested server to client (download) and results were similar.
2.4ghz WiFi channel 1 and then channel 6
Monitor Dell 1907FPWiFi channel 1
ResolutionHZ Throughput
no hdmi no hdmi 47mbs
1280x102475.025Hz13mbs
1280x102460.020Hz13mbs
1024x76875.029Hz49mbs
1024x76860.004Hz0mbsConnected but unable to send traffic
720x48060.000Hz18mbs
720x48059.940Hz17mbs
Running the same tests the goodpi WiFi speed was consistently between 44 and 55 mbs at all settings.
Note the test 1024x768 at 60Hz:
no traffic is passing. The connection is up and iwconfig showed a Bit Rate of 61Mb/s.
Rebooting at this resolution/refresh rate and slowpi could not connect to WiFi 2.4 until I changed the refresh rate to 75.029Hz.
I then changed the WIFi channel to 6.
Now on the Dell 1907FP 1024x768 test at 75.029Hz no traffic is passed.
At 60Hz throughput is normal. A reversal of the channel 1 test above.
Throughput for the other resolutions on channel 6 was the same as reported above.
Hackaday suggested channel 11 but channel 11 is congested in my vicinity and by now I had enough results.
Dell G3223Q 4k monitor WiFi Channel 1 testing
Connected via the official Raspberry PI Micro HDMI to HDMI Adapter into a HDMI cable.
The same resolutions and refresh rates as above where the monitor supported it
Plus 4k at 30Hz, 2K at 30 Hz, and 1920x1080 at 60Hz and 120Hz.
The only resolution that had an issue was 1024X768 at 60Hz. Slowpi could not send/receive traffic at this setting. All other resolutions/refresh rates the speed was as expected.
Slowpi has major issues with WiFi and the Cable Matters HDMI to VGA adapter and an issue with an official Raspberry PI HDMI cable at one setting.
Goodpi had no issues with either HDMI cable.
Try changing the resolution and/or the refresh rate for the monitor.
Try a different HDMI cable
Try changing the WiFi channel on the access point.
See the article from 2019: https://hackaday.com/2019/11/28/raspber ... own-wifi/
The comments hints the issue was ‘fixed’ but offers no link.
Perhaps this is related to the older B0 version of the SOC.
https://www.jeffgeerling.com/blog/2021/ ... 0-stepping
A story of 2 PI’s.
Purchased 2 PI 4B 4gb from the same seller in December 2023 second hand.
Both boards passed extended stressberry and video playback testing.
It was when checking WIFI speed that the fun started.
Let's call them:
slowpi = has issues with WIFI speed at 2.4 ghz
and goodpi = no issues
For both units 5ghz WiFi speed is unaffected.
Similarities between the units:
Hardware core speed 1.8ghz
EEPROM updated to: VL805
Differences between the units:
Slowpi:
SOC is the B0 version
Bootloader: “Tue Feb 16 01:23:36 PM UTC 2021 (1613481816)”
Note: that after upgrading the bootloader to the latest on slowpi made no difference in test results. Updated to: “Wed Jan 11 05:40:52 PM UTC 2023 (1673458852)”
Goodpi:
SOC is the newer C0 version
Bootloader: “Thu Apr 29 04:11:25 PM UTC 2021 (1619712685)”
I did not upgrade this yet.
I only found out about B0 and C0 SOC versions after all testing. I think this difference in boards is the most probable cause of slowpi. Perhaps they added more HDMI shielding when they updated the SOC but I can’t find anything that indicates it. The other possibility is the B0 Slowpi has a defect.
Test Setup:
Bookworm updated to 2024-01
Testing with iperf3 to a server. The server is connected to the WiFi Access Point via ethernet at 1gbs
Canakit Raspberry PI 4B power supply (from my other 4B Kit)
Cable Matters HDMI to VGA adapter
VGA Monitor: Dell 1907FPt - an old 19" Fullscreen (1280 x 1024)
I also tested with a Dell G3223Q 4K monitor and different cable separately. See below.
Screen resolution and refresh rate was changed using the Screen Configuration in the GUI.
iperf3 test results in the chart were run for 30 seconds client PI to server (upload).
Tested server to client (download) and results were similar.
2.4ghz WiFi channel 1 and then channel 6
Monitor Dell 1907FPWiFi channel 1
ResolutionHZ Throughput
no hdmi no hdmi 47mbs
1280x102475.025Hz13mbs
1280x102460.020Hz13mbs
1024x76875.029Hz49mbs
1024x76860.004Hz0mbsConnected but unable to send traffic
720x48060.000Hz18mbs
720x48059.940Hz17mbs
Running the same tests the goodpi WiFi speed was consistently between 44 and 55 mbs at all settings.
Note the test 1024x768 at 60Hz:
no traffic is passing. The connection is up and iwconfig showed a Bit Rate of 61Mb/s.
Rebooting at this resolution/refresh rate and slowpi could not connect to WiFi 2.4 until I changed the refresh rate to 75.029Hz.
I then changed the WIFi channel to 6.
Now on the Dell 1907FP 1024x768 test at 75.029Hz no traffic is passed.
At 60Hz throughput is normal. A reversal of the channel 1 test above.
Throughput for the other resolutions on channel 6 was the same as reported above.
Hackaday suggested channel 11 but channel 11 is congested in my vicinity and by now I had enough results.
Dell G3223Q 4k monitor WiFi Channel 1 testing
Connected via the official Raspberry PI Micro HDMI to HDMI Adapter into a HDMI cable.
The same resolutions and refresh rates as above where the monitor supported it
Plus 4k at 30Hz, 2K at 30 Hz, and 1920x1080 at 60Hz and 120Hz.
The only resolution that had an issue was 1024X768 at 60Hz. Slowpi could not send/receive traffic at this setting. All other resolutions/refresh rates the speed was as expected.
Slowpi has major issues with WiFi and the Cable Matters HDMI to VGA adapter and an issue with an official Raspberry PI HDMI cable at one setting.
Goodpi had no issues with either HDMI cable.
Statistics: Posted by jd1328 — Sat Feb 24, 2024 9:09 pm — Replies 0 — Views 8