[TCkDfz]

Yesterday I upgraded from r26653 to r27147. Interestingly for the first time my 5GHz LED worked after upgrading from a previous DD-WRT build. The LED has always worked when upgrading from ASUS to DD-WRT firmware. In both scenarios after I configure my wireless settings the LED stops working.

My upgrade routine is to erase the nvram and capture the new defaults. Occasionally a setting will be added, deleted, or changed. The differences between 26653 and 27147 are significant:

Added:
et_txq_thresh=1024
router_style_dark=0

Removed:
wl2_ampdu_rr_rtylimit_tid=2 2 2 2 2 2 2 2
wl2_ampdu_rtylimit_tid=5 5 5 5 5 5 5 5
wl2_ampdu=auto
wl2_amsdu=auto
wl2_antdiv=3
wl2_ap_isolate=0
wl2_atf=1
wl2_bss_opmode_cap_reqd=0
wl2_bw_cap=255
wl2_cal_period=0
wl2_frameburst=off
wl2_gmode_protection=auto
wl2_itxbf=0
wl2_maxassoc=128
wl2_mode=ap
wl2_nband=1
wl2_nbw_cap=1
wl2_nbw=20
wl2_nctrlsb=none
wl2_net_mode=mixed
wl2_nmcsidx=-1
wl2_nmode=-1
wl2_nreqd=0
wl2_obss_coex=0
wl2_rifs_advert=auto
wl2_rx_amsdu_in_ampdu=auto
wl2_rxchain_pwrsave_enable=0
wl2_shortslot=auto
wl2_ssid=dd-wrt
wl2_stbc_rx=1
wl2_stbc_tx=auto
wl2_turbo_qam=1
wl2_txant=3
wl2_txbf_bfe_cap=1
wl2_txbf_bfr_cap=1
wl2_txbf=0
wl2_txchain_pwrsave_enable=0
wl2_txpwr=71
wl2_vlan_prio_mode=off
wl2_web_filter=0
wl2_wme_ap_be=15 63 3 0 0 off
wl2_wme_ap_bk=15 1023 7 0 0 off
wl2_wme_ap_vi=7 15 1 6016 3008 off
wl2_wme_ap_vo=3 7 1 3264 1504 off
wl2_wme_apsd=on
wl2_wme_no_ack=off
wl2_wme_sta_be=15 1023 3 0 0 off
wl2_wme_sta_bk=15 1023 7 0 0 off
wl2_wme_sta_vi=7 15 2 6016 3008 off
wl2_wme_sta_vo=3 7 2 3264 1504 off
wl2_wme_txp_be=7 3 4 2 0
wl2_wme_txp_bk=7 3 4 2 0
wl2_wme_txp_vi=7 3 4 2 0
wl2_wme_txp_vo=7 3 4 2 0
wl2_wmf_bss_enable=0
wl2_wmf_igmpq_filter=0
wl2_wmf_mdata_sendup=0
wl2_wmf_ucast_upnp=1
wl2_wmf_ucigmp_query=0

et_txq_thresh=1024, which was added, wasn't in any prior version that I could find. The removed settings were present in at least 26653 and 26866. Configuring WiFi could add them but there appears to be a problem that entering anything in the DNSMasq options field in the web interface breaks DNS so I didn't test further.

I hope this information helps find a permanent fix for the 5GHz LED.