How to fix ath9k filtering issue on older cards: Find your macVersion and add it to this code in ath9k/recv.c

                /* The following may also be needed for other older chips */
-                if (sc->sc_ah->hw_version.macVersion == AR_SREV_VERSION_9160)
+                if (sc->sc_ah->hw_version.macVersion == AR_SREV_VERSION_9160 ||
+                    sc->sc_ah->hw_version.macVersion == AR_SREV_VERSION_XXXX)
                        rfilt |= ATH9K_RX_FILTER_PROM;

For instance, for our PCIE card the code to use is AR_SREV_VERSION_5416_PCIE If unsure, you can just remove the if guard altogether.