[FS#253] Multicast over wireless ceases to work properly after a while on ath9k with many clients connected

[LEDE Bugs]

The following task has a new comment added:

FS#253 - Multicast over wireless ceases to work properly after a while on ath9k with many clients connected
User who did this - Mathias Kresin (mkresin)

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Michael, would you please test again! According to Neils edit, this one should be fixed in the meantime.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=253#comment1064