localsend
Windows 11 24H2 connectivity broken after InPlace-Upgrade from 23H2 (discovery/transfer) when used with MalwareBytes Firewall Control
Describe the bug
Phone doesn't find host. After restarting service on host, host is found. When then trying to transfer a file, the request does not reach the host (GUI-wise).
To reproduce
App version 1.17 on Windows and Android. Seems related to 24H2, since I just upgraded to that. My firewall control is MalwareBytes Firewall Control, so a layer on top of the default WFW.
Expected behavior
An error message somewhere, or a firewall request in the stock UX after/during installation.
Screenshots
No response
Desktop (please complete the following information)
W11 24H2 App version 1.17
Smartphone (please complete the following information)
Pixel 8a, Android 15 App version 1.17
Additional context
MWB WFC is configured to block by default yet ask if requests are recognized - this works fine for all other apps, and worked just as fine with LocalSend up until 23H2. After InPlace-Upgrading to 24H2, the connection broke.
I could bring the client (Android) to see the host (Windows) only if specifically restarting the service on the host during the discovery attempts. Which already is weird af - either the firewall allows it or it doesn't?!
The firewall (MWB WFW layer orchestrating stock WFW) has permissions for outbound and incoming traffic for the network LocalSend is working on (Private). I discovered the WiFi adapter being reset to Public after the 24H2 upgrade, changing it to Private didn't change the behaviour though.
What worked in the end: Manually adding a "Allow through WF" rule for the Private network. I am unsure if this is a LocalSend issue, stock WFW issue or something with MWB WFC. Since it worked flawlessly before I am leaning heavily towards Bill Gates.
Just for further clarification: All network settings - so IP addresses, DHCP, randomized MAC etc. all stayed the same (static and IPv4 only) and especially did not change on the host. I verified that after the network type was switched to Public by the upgrade. No changes were made on the Android phone. Both clients were rebooted multiple times (proper full boot on Windows).
Adding this bug report for visibility in case others find their way here with the same/a similar issue.
^ = example of broken communication, tcpdump taken on PC before the firewall rule was added.
MWB WFC configuration (also deleted and recreated, no change)
Solution: Implement via stock WFW UI.
pfirewall_private_with_drops.log
WFW log before rule has been implemented.
Afterwards, nothing is logged as dropped because the connection (discovery/transfer) works properly then.