[FS#714] ARP/Broadcast does not reach other clients in the same WLAN

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Jake (Jakeler) 

Attached to Project - LEDE Project
Summary - ARP/Broadcast does not reach other clients in the same WLAN
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - High
Priority - Very Low
Reported Version - All
Due in Version - Undecided
Due Date - Undecided
Details - I have the default bridge with ethernet and WLAN in it. When i try to send data from a client to another, both connected to the same WLAN SSID, it doesn't work (Destination unreachable). 
Wireshark shows that it sends endless ARP requests to Broadcast, but the other clients in that WLAN never get it (and therefore can't answer). The broadcast gets still delivery to every client connected through Ethernet. If i create a second WLAN SSID (even on the same adapter) and and add it to the bridge, it gets also all broadcast packets from the other WLAN... 
So if i put the 2 clients in different WLAN SSIDs or ethernet they get the broadcast from each other, but not when both are connected to the same.

The isolate option is not set in the wireless config.
Archer C5 v1 with latest LEDE snapshot (no difference to 17.01 stable or rc).

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=714