Not sure if it's better to ask here or on the network engineering exchange, but since I'm looking for an Ubuntu-specific solution, here goes.

Configuration: Ubuntu 16.04, WiFi hotspot via hostapd, dnsmasq serving DNS/DHCP, Ethernet port and wlan bridged via /etc/network/interfaces

Problem: When a certain wired Ethernet device is plugged into the same network the WiFi hotspot becomes unusable. This device, a sensor, broadcasts UDP packets to (the problem persists if I have it broadcast to The symptoms are: wireless clients are unable to ping the hotspot or to obtain IP addresses (tcpdump shows DHCPDISCOVER and DHCPOFFER packets but no DHCPREQUEST or DHCPACK follow). Wired connections works without problems.

I worked around this by configuring the sensor to broadcast to a specific IP (e.g. but several different devs on separate machines connect for development and it's inconvenient to change the setting every time we change devs/machines. I want to understand why this is happening (the bridged WiFi adapter chokes on retransmitting the UDP broadcast traffic?) and how I can prevent this from happening - no one will be consuming the UDP traffic over the WiFi link. Perhaps I need to configure the bridge to block UDP broadcast from going over the WiFi interface - without interfering with other UDP traffic like NTP or DHCP?

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.