I'm having regular issues with my R8000 where the wifi goes out. I am attaching dmesg logs, mem output, and wi scan output. The reason for memory output is because the wi output says 'out of memory'. Hopefully, it makes sense to someone. 
BusyBox v1.25.1 () built-in shell (ash)
_________
/ /\ _ ___ ___ ___
/ LE / \ | | | __| \| __|
/ DE / \ | |__| _|| |) | _|
/________/ LE \ |____|___|___/|___| lede-project.org
\ \ DE /
\ LE \ / -----------------------------------------------------------
\ DE \ / Reboot (17.01.5, r3919-38e704be71)
\________\/ -----------------------------------------------------------
root@LEDE:~# iw dev
phy#2
Interface wlan2
ifindex 8
wdev 0x200000001
addr e8:fc:af:fc:4f:ab
type managed
channel 36 (5180 MHz), width: 20 MHz, center1: 5180 MHz
phy#1
Interface wlan1
ifindex 7
wdev 0x100000001
addr e8:fc:af:fc:4f:ac
ssid xyz_pub
type AP
phy#0
Interface wlan0
ifindex 6
wdev 0x1
addr e8:fc:af:fc:4f:ad
type managed
channel 36 (5180 MHz), width: 20 MHz, center1: 5180 MHz
root@LEDE:~# iw dev wlan1 scan
command failed: Out of memory (-12)
root@LEDE:~# free
total used free shared buffers cached
Mem: 255508 39568 215940 100 2124 5832
-/+ buffers/cache: 31612 223896
Swap: 0 0 0
root@LEDE:~#
[ 21.240070] br-lan_gen: port 2(wlan1) entered forwarding state
[ 21.245993] br-lan_gen: port 2(wlan1) entered forwarding state
[ 23.242048] br-lan_gen: port 2(wlan1) entered forwarding state
[11161.002462] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11163.002353] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11163.010125] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11185.522363] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11187.522357] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11187.530129] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11241.242368] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11243.242366] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11243.250142] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11295.342378] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11297.342378] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11297.350151] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11299.352381] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11301.352378] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11301.360153] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11332.472389] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11334.472398] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11334.480170] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11419.762402] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11421.762404] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11421.770174] brcmfmac: brcmf_cfg80211_get_station: GET STA INFO failed, -5
[11427.312404] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11427.320175] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11429.322404] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11429.330183] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11431.332406] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11431.340252] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11433.342409] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11433.350186] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11435.352406] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11435.360182] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11437.362414] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11437.370189] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11439.372406] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11439.380177] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11441.382409] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11441.390183] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11443.392408] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11443.400180] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11445.402412] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11445.410298] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11447.412409] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11447.420184] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11449.422430] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11449.430206] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11451.432412] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11451.440188] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11453.442412] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11453.450185] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11454.402494] brcmfmac: brcmf_netdev_wait_pend8021x: Timed out waiting for no pending 802.1x packets
[11456.402417] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11456.410189] brcmfmac: send_key_to_dongle: wsec_key error (-5)
[11458.412410] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11458.420185] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11460.422411] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11460.430184] brcmfmac: brcmf_cfg80211_change_station: Setting SCB (de-)authorize failed, -5
[11462.432413] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11462.440190] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11464.442438] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11464.450213] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11466.452427] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11466.460202] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11468.462417] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11468.470190] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11470.472416] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11470.480187] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11472.482416] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11472.490194] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11474.492415] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11474.500190] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11476.502416] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11476.510188] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11478.512416] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11478.520193] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11480.522422] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11480.530200] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11482.532417] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11482.540188] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11484.542416] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11484.550186] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11486.552422] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11486.560191] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11488.562418] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11488.570189] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11490.572418] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11490.580196] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[11492.582419] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[11492.590193] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[27639.287638] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27639.295418] brcmfmac: brcmf_cfg80211_del_station: SCB_DEAUTHENTICATE_FOR_REASON failed -5
[27639.337873] device wlan1 left promiscuous mode
[27639.342449] br-lan_gen: port 2(wlan1) entered disabled state
[27641.347589] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27641.355375] brcmfmac: _brcmf_set_multicast_list: Setting mcast_list failed, -5
[27643.357591] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27643.365373] brcmfmac: _brcmf_set_multicast_list: Setting allmulti failed, -5
[27645.367590] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27645.375377] brcmfmac: _brcmf_set_multicast_list: Setting BRCMF_C_SET_PROMISC failed, -5
[27647.377593] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27649.377586] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27649.385363] brcmfmac: brcmf_cfg80211_stop_ap: SET SSID error (-5)
[27651.387594] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27651.395368] brcmfmac: brcmf_cfg80211_stop_ap: BRCMF_C_DOWN error -5
[27653.397605] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27653.405439] brcmfmac: brcmf_cfg80211_stop_ap: setting AP mode failed -5
[27655.407600] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27655.415371] brcmfmac: brcmf_cfg80211_stop_ap: setting INFRA mode failed -5
[27657.417597] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27659.417597] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27661.417598] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27661.425413] brcmfmac: brcmf_cfg80211_stop_ap: BRCMF_C_UP error -5
[27663.427597] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27663.435367] brcmfmac: brcmf_set_mpc: fail to set mpc
[27665.437598] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27667.437596] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27669.445661] brcmfmac: brcmf_msgbuf_query_dcmd: Timeout on response for query command
[27669.453506] brcmfmac: _brcmf_set_multicast_list: Setting mcast_list failed, -5
[27669.460781] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27669.468377] brcmfmac: _brcmf_set_multicast_list: Setting allmulti failed, -12
[27669.475532] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27669.483128] brcmfmac: _brcmf_set_multicast_list: Setting BRCMF_C_SET_PROMISC failed, -12
[27669.491258] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27669.498860] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27670.837824] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
[27672.999652] net_ratelimit: 88 callbacks suppressed
[27673.004466] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.012115] brcmfmac: brcmf_cfg80211_get_channel: chanspec failed (-12)
[27673.019271] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.026932] brcmfmac: brcmf_cfg80211_get_channel: chanspec failed (-12)
[27673.034204] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.041842] brcmfmac: brcmf_netdev_set_mac_address: Setting cur_etheraddr failed, -12
[27673.050075] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.057716] brcmfmac: brcmf_cfg80211_get_channel: chanspec failed (-12)
[27673.465674] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.473345] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27673.885885] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
[27683.984530] net_ratelimit: 43 callbacks suppressed
[27683.989341] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27683.996993] brcmfmac: _brcmf_set_multicast_list: Setting mcast_list failed, -12
[27684.004321] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27684.011919] brcmfmac: _brcmf_set_multicast_list: Setting allmulti failed, -12
[27684.019078] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27684.026674] brcmfmac: _brcmf_set_multicast_list: Setting BRCMF_C_SET_PROMISC failed, -12
[27684.395679] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27684.403278] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27684.410894] brcmfmac: brcmf_cfg80211_stop_ap: SET SSID error (-12)
[27684.417096] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[27686.875861] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
[54019.312677] net_ratelimit: 67 callbacks suppressed
[54019.317486] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[54019.325178] brcmfmac: brcmf_cfg80211_get_channel: chanspec failed (-12)
[54019.331817] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[54019.339422] brcmfmac: brcmf_cfg80211_get_tx_power: error (-12)
[54077.536382] brcmfmac: brcmf_msgbuf_tx_ioctl: Failed to reserve space in commonring
[54077.544047] brcmfmac: brcmf_do_escan: error (-12)
[54077.548767] brcmfmac: brcmf_cfg80211_scan: scan error (-12)