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RPi4 SSH disconnecting

tsengf

October 29, 2022 06:36

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Hi, I have a RPi4 with a power supply from CanaKit. I have Logitech Media Server running on this RPi connected via WiFi. I have not had any issues with the unit.

Recently, I installed the Digi+ HAT. After installing the HAT, my SSH connection into the RPi exhibits two symptoms. First, I would frequently experience non-responsiveness from the SSH terminal. For example, when I run apt update, the command would start but the terminal output may stop in the middle of the process. Secondly, if the terminal ultimately does not recover, I would get the "client_loop: send disconnect: Connection reset by peer" message and my connection would drop. This never happened prior to installing the HAT.

I originally thought that perhaps the wireless network connection became flaky after the installation of the HAT. The strange thing about this is that LMS experiences no disruptions. I can still connect to the LMS web interface even during the SSH disconnects. Music streamed from online sources are not affected when the SSH connection drops.

Has anyone experienced this or know of a solution? Thanks in advance.

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5 comments

• 0
  
  tsengf October 30, 2022 21:49

  As a followup, the power supply that I'm using was included with the CanaKit. It's 5.1V at 3.5A. I have also tried swapping out the RPi4 and power supply with another RPi4 and power supply. I get the same behavior. I have also tried connecting to the RPi4 via ethernet. I also experience the same behavior over ethernet. This rules out any issues with the WiFi connectivity.

  Again, network connectivity to LMS is fine but when I SSH in via the terminal, the SSH connection does not appear to be stable. I'm beginning to wonder if the Digi+ has some kind of strange interaction that causes the SSH connection to become flaky.

  Anyone?

• 0
  
  tsengf November 01, 2022 15:33

  I wanted to provide an update. I was already caught up on updates when I made my original post. Yesterday, I updated again and there was a new kernel.

  Get:1 http://archive.raspberrypi.org/debian bullseye/main arm64 dhcpcd5 arm64 1:8.1.2-1+rpt9 [163 kB]
  Get:2 http://archive.raspberrypi.org/debian bullseye/main arm64 linux-libc-dev arm64 1:1.20221028-1 [1073 kB]
  Get:3 http://archive.raspberrypi.org/debian bullseye/main arm64 raspberrypi-kernel arm64 1:1.20221028-1 [26.7 MB] 
  Get:4 http://archive.raspberrypi.org/debian bullseye/main arm64 raspberrypi-bootloader arm64 1:1.20221028-1 [4541 kB] 

  With the new kernel, I am no longer experiencing the SSH connection issues on the RPi4 with the Digi+. Unfortunately, I did not take note of the previous kernel version.

• 0
  
  tsengf November 02, 2022 04:11

  I spoke too soon. It appears the updated kernel has nothing to do with resolving this issue. Next step is to enable sshd logs to see what's happening to the connection.

• 0
  
  tsengf November 05, 2022 05:30

  I decided to do a test using a fresh install of Raspbian.

  • Release date: September 22nd 2022
  • System: 64-bit
  • Kernel version: 5.15
  • Debian version: 11 (bullseye)

   

  The only change I made to the system was added the line "dtoverlay=hifiberry-digi" to /boot/config.txt. Running the vanilla image, I experienced no delay problems while connected via SSH through the terminal. I let this running for over 24 hours just in case the problem was intermittent.

  After I run apt update; apt upgrade, the slowness over the terminal reappeared. It seems like some package has caused this strange behavior. This of course happens only on my Pi4 which has the Digi+ attached.

  Edited by tsengf November 05, 2022 05:30
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  tsengf November 10, 2022 05:34

  My issue is resolved. I came across this post https://forums.raspberrypi.com/viewtopic.php?t=138631&start=100 where someone suggested adding the following line to the bottom of /etc/ssh/sshd_config.

  IPQoS cs0 cs0

  This resolves the intermittent SSH issues I encountered. Some notes on the original issue

  • When connected via SSH to the impacted RPi, the hangs on the terminal happened on both WiFi and ethernet connections; the hangs usually resulted in SSH getting disconnected
  • During the disconnects, other means of connecting to the RPi still work (ie. there are no problems with the RPi's network connectivity)
  • The hangs associated with SSH only manifest if the Digi+ HAT is installed. I did not experience any intermittent issues when the HAT is removed.