EDIT/SOLVED: The culprit turned out to be a faulty offbrand 5V 3A DC power adapter. I tried another adapter - incidentally, one that I use to charge my smartphone - and the hissing sound was gone. My other router - also a Raspberry Pi 4B - uses the same power adapter as the one that started malfunctioning/hissing was using, but it is quiet and operates normally. At the very least I draw the following three conclusions:

1. 5V 3A is enough to run a Raspberry Pi 4B as a router with constant heavy TX/RX of at least a couple of terabytes per day.
2. I should be prepared for the other offbrand power adapter - namely the one that came with the OkDo bundle - to fail within a year or so.
3. There are really nice people here that give quick and elaborate responses! Thank you all! 🩵

The linked file is a recording of a hissing sound that my Raspberry Pi 4 started to make sometime during the last 24 hours. Another symptom is that the power on and CPU activity LEDs are out. It is not running hot. It doesn’t have an internal fan. It is being cooled by six PC chassis fans. It is running OpenWRT. It has been pumping Linux ISOs in and out non stop for about four months.

I have tried cleaning it by dedusting it. I have also tried rebooting it. While rebooting, it squeals like a mouse, like it was suffering but the LEDs function properly. As soon as it loads user space though and resume routing, they turn off and the hissing sound continues.

Here are some system logs with severities warning and error. As you can see, the logs are from the 15th and I don’t think any of them pertain to the hissing sound and/or the LEDs.

WARNING  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    0.196065] pci_bus 0000:01: supply vpcie3v3 not found, using dummy regulator  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    0.196201] pci_bus 0000:01: supply vpcie3v3aux not found, using dummy regulator  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    0.196257] pci_bus 0000:01: supply vpcie12v not found, using dummy regulator  
[May 15, 2026, 23:29:12 GMT+2] user.warn: [    7.225917] urandom-seed: Seeding with /etc/urandom.seed  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    8.327998] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    8.365104] brcmutil: loading out-of-tree module taints kernel.  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    8.780919] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin failed with error -2  
[May 15, 2026, 23:29:12 GMT+2] kern.warn: [    8.792642] brcmfmac mmc1:0001:1: Falling back to sysfs fallback for: brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin  
[May 15, 2026, 23:29:12 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry  
[May 15, 2026, 23:29:18 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry  
[May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0!  
[May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: rfc9096: br-lan: piofile updated  
[May 15, 2026, 23:29:37 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0!  
[May 15, 2026, 23:29:53 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0!  
[May 15, 2026, 23:30:18 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0!  

ERROR  
[May 15, 2026, 23:29:12 GMT+2] kern.err: [    0.307942] bcm2708_fb soc:fb: Unable to determine number of FBs. Disabling driver.  
[May 15, 2026, 23:29:12 GMT+2] kern.err: [    0.307968] bcm2708_fb soc:fb: probe with driver bcm2708_fb failed with error -2  
[May 15, 2026, 23:29:12 GMT+2] user.err: [    7.197094] insmod: module is already loaded - fat  
[May 15, 2026, 23:29:12 GMT+2] user.err: [    7.204851] insmod: module is already loaded - vfat  
[May 15, 2026, 23:29:22 GMT+2] daemon.err: procd: Got unexpected signal 1  

Judging by the squealing during reboot, I believe it to be either the CPU or memory, although I have never hears memory make sound, while CPUs, I have.

Edit: The solution in my case was to run these commands:

sudo apt update
sudo apt install linux-image-rpi-v8 linux-headers-rpi-v8

The new kernel wasn't used after rebooting though, so I had to edit /boot/config.txt and add:

# New kernel (test)
kernel=vmlinuz-6.12.75+rpt-rpi-v8
initramfs initrd.img-6.12.75+rpt-rpi-v8 followkernel

I'll figure out how to make it so I don't have to manually keep config.txt updated but for now, I'm happy to have a process to stay up to date with current kernels.

/edit

Reading about the latest Copy Fail security vulnerability I realised I was overdue a check on my system. It turns out I had even bigger problems - I was still on Debian 10/Buster.

To solve it I updated my apt list to contain: deb http://archive.raspberrypi.org/debian/ bookworm main

But after doing this, updating and doing a full upgrade, my kernel is still 6.1.21.

I'm now reading that I should not have upgraded from bullseye to bookworm, so what is the easiest way forward from here? If there is a documented set of steps for this scenario I'd appreciate a link. I have a lot of services and scripts so reinstalling from scratch is not really an option.

uname -a
Linux 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux.

cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"``___

The United States FCC recently announced a ban on new consumer-grade routers produced outside of the US. This does not affect existing devices that were already authorized, and there is a carve-out for manufacturers to apply for a conditional approval. It's difficult to say what the medium or longterm effects of the ban will be.

This got me thinking about what could be used as a makeshift router in a pinch. As it so happens, any computer that can run Linux and has networking interfaces can function as a router. This blog post by Noah Baily documents the process using various old computers and components as custom routers over the years.

These makeshift routers are not going to win any bandwidth speed races, but they're perfectly capable of routing traffic for IoT devices or basic browsing. They're also useful for capturing traffic to analyze or sharing internet access from WiFi to Ethernet or vice-versa.

This guide documents the setup process and capabilities of using a Raspberry Pi as a router. It does not require a particularly powerful computer, even the older Pi 3 B+ that lots of us have tucked away in an old parts bin works fine for this.

This board turns a Raspberry Pi CM5 into a NAS with support for 5 HDDs

I'm running octopi on an rpi zero 2 w it had been working flawlessly for weeks until I unplugged it to move the printer. Now it won't connect to Wi-Fi sometimes. If I connect a monitor it will connect. If I connect the monitor after booting it has no network IP address just the 127... Local address. I've gotten it to connect one time without a monitor but it was in the wrong location. I thought it might be proximity related, and it still could be, but that doesn't explain why it doesn't always connect near my Wi-Fi access point where it was working before. I've tried multiple other power supplies and with the printer both turned on and disconnected.

I guess using LVM on an old raspberry pi 3B+ was not the smartest idea :/ ! As expected the pi 3b+ can handle qbittorrent and piHole without to much load average...

After switching from LVM+EXT4 to a single EXT4 partition, I can download, check file integrity and resolve DNS at the same time without my dns resolution hanging !

Solution:

• Install piHoleOS on a simpler filesystem without LVM (ext4)
• Take qbittorrent out of docker and install it barebone on the device (qbittorrent-nox)

Hello :))

I'm relatively new to the pi and all the ecosystem (ARM, SBC...) and I'm kinda intrigued on what's happening here if someone has some info to share.

I generally work on debian for my server stuff but found an old never used RPi 3B+ in one of my boxes. Installed RPi OS lite based on debian bookworm and docker with the pihole container as DNS server for my home network.

Works great and does hold all my DNS requests without issues. However, yesterday I migrated my qbittorrent stuff (mostly linux ISO 😅) on the RPi, on an external HDD over USB.

While uploading works fine without issues for +/- 100 torrent files, when downloading OR checking the files integrity the RPi is chocking really hard making the DNS request slowdown and even unresponsive...

I did some search and from my findings the USB is a hard bottleneck for file transfer on the pi 3b+ and qbittorrent in a container adds alot of overheat too, so I checked and moved everything out of the container and installed qbittorrent-nox which does improve the situation but it still makes the DNS request on pihole impossible when downloading or checking file integrity.

I this some kind of bug, known issue? RPi is cool stuff but If it can't hold or stand a medium hungry service, that's kinda a bummer... It's not doing that much of work, It's just resolving DNS and downloading a file over the torrent protocol.

Somone similar issue, observation, insight or solution? Or is the pi not meant to hold a torrenting service?

Does it work on a Pi5 running systems like the Raspbian/Raspberry Pi OS or KonstaKANG's LineageOS?

Don't have the device (yet?), but Grayjay would be one of the main uses for it for me, so concerned I might be wasting money, thus asking if anyone would know.

I have a pile of hard drives sitting around that need to be securely wiped. Does anyone know of something similar to DBAN or ShredOS for ARM that I can use to turn a Pi into a disk wipe station? It doesn't need to be a dedicated OS, just a package that I can run on top of armbian or whatever.