Problem Summary:
I have an application where a Windows PC sends UDP broadcasts (port 48888) to wake up Raspberry Pi5 devices on the network. The PC sends a broadcast every ~5 seconds when active.
The issue: Intermittently, the Pi stops receiving UDP broadcasts for 5-10 minutes at a time, then suddenly starts working again. When there are multiple Pis, they all recover at the same time.
Observations:
Ping (unicast) seems to work even when the broadcasts are not. - During the failure window, I can ping the Pi from the PC or another Pi and vice versa
During failure, I can still connect to the devices with the Pi remote connect
tcpdump shows nothing - Running sudo tcpdump -i wlan0 udp port 48888 on the Pi shows zero packets during the failure
Broadcast test fails - Testing with echo "PING" | socat - UDP4-DATAGRAM:255.255.255.255:48888,broadcast from another device also doesn't reach the Pi
Pi-to-Pi broadcast also fails - Two wireless Pis cannot reach each other with broadcasts during the failure
All Pis recover simultaneously
Environment Details
The Pi5 are connecting on 2.4 GHz (channel 11, 2462 MHz):
BSS 40:ed:00:e4:c0:00(on wlan0) -- associated freq: 2462 bss flags: short-preamble short-slot-time signal: -42.00 dBm
There are 3 PCs and 3 Pi5s on the same network (and some other devices)
The network has Fortinet switch and a firewall with no special configurations.
What I've Ruled Out
Same VLAN - All devices confirmed on 192.168.30.x with same subnet mask
No storm control - There should not be any broadcast storm control
Wi-Fi connection is stable - journalctl -u NetworkManager shows no disconnects/reconnects during failures
Not signal strength - Pi shows -42 dBm signal, well within acceptable range
Switching the PC from wired to wireless does not help
Switching the wifi power save off does not help
This does not seem to happen on all places and when testing with my home network, I'm not able to reproduce this issue. Any suggestions on what might cause this type of behaviour?
I have an application where a Windows PC sends UDP broadcasts (port 48888) to wake up Raspberry Pi5 devices on the network. The PC sends a broadcast every ~5 seconds when active.
The issue: Intermittently, the Pi stops receiving UDP broadcasts for 5-10 minutes at a time, then suddenly starts working again. When there are multiple Pis, they all recover at the same time.
Observations:
Ping (unicast) seems to work even when the broadcasts are not. - During the failure window, I can ping the Pi from the PC or another Pi and vice versa
During failure, I can still connect to the devices with the Pi remote connect
tcpdump shows nothing - Running sudo tcpdump -i wlan0 udp port 48888 on the Pi shows zero packets during the failure
Broadcast test fails - Testing with echo "PING" | socat - UDP4-DATAGRAM:255.255.255.255:48888,broadcast from another device also doesn't reach the Pi
Pi-to-Pi broadcast also fails - Two wireless Pis cannot reach each other with broadcasts during the failure
All Pis recover simultaneously
Environment Details
The Pi5 are connecting on 2.4 GHz (channel 11, 2462 MHz):
BSS 40:ed:00:e4:c0:00(on wlan0) -- associated freq: 2462 bss flags: short-preamble short-slot-time signal: -42.00 dBm
There are 3 PCs and 3 Pi5s on the same network (and some other devices)
The network has Fortinet switch and a firewall with no special configurations.
What I've Ruled Out
Same VLAN - All devices confirmed on 192.168.30.x with same subnet mask
No storm control - There should not be any broadcast storm control
Wi-Fi connection is stable - journalctl -u NetworkManager shows no disconnects/reconnects during failures
Not signal strength - Pi shows -42 dBm signal, well within acceptable range
Switching the PC from wired to wireless does not help
Switching the wifi power save off does not help
This does not seem to happen on all places and when testing with my home network, I'm not able to reproduce this issue. Any suggestions on what might cause this type of behaviour?
Statistics: Posted by Scooter0987987 — Sun Jan 25, 2026 5:20 pm — Replies 0 — Views 38