[Nexus 6P Q&A, Help & Troubleshooting] Asitaka:
Back to stock, it's persisting.. I looked in catlog and see this:

05-04 09:11:01.380 1431 3560 D ConnectivityService: releasing NetworkRequest [ REQUEST id=28, legacyType=3, [ Transports: CELLULAR Capabilities: SUPL&NOT_RESTRICTED&TRUSTED&NOT_VPN] ]

05-04 09:11:01.380 1431 1443 I GnssLocationProvider: WakeLock released by handleMessage(15, 2, null)

05-04 09:11:01.381 1431 3560 D ConnectivityService: Sending DISCONNECTED broadcast for type 3 NetworkAgentInfo [MOBILE (HSDPA) - 111] isDefaultNetwork=false

05-04 09:11:01.411 13811 13811 D MusicLifecycle: com.google.android.music.net.NetworkConnectivityMonitor$NetworkChangedReceiver generated event: Broadcast received with context com.google.android.music.MusicApplication@19439af and intent Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x4000010 (has extras) }

05-04 09:11:01.419 3863 3863 D MccTable: updateMccMncConfiguration mccmnc='null' fromServiceState=true

05-04 09:11:01.419 3863 3863 D MccTable: WIFI_COUNTRY_CODE set to

05-04 09:11:01.419 1431 14829 I WifiService: WifiService trying to set country code to with persist set to false

05-04 09:11:01.426 18316 18316 V BugleThrottledAction: CountryCodeDetectorAction scheduled to run now.

05-04 09:11:01.426 18316 18316 D BugleThrottledAction: CountryCodeDetectorAction already scheduled in 0ms, not scheduling it again.

05-04 09:11:01.426 14746 14746 D HeadsetPhoneState: sendDeviceStateChanged. mService=0 mSignal=0 mRoam=0 mBatteryCharge=4

05-04 09:11:01.426 14746 14746 D HeadsetPhoneState: sendDeviceStateChanged. mService=0 mSignal=0 mRoam=0 mBatteryCharge=4

05-04 09:11:01.434 1431 1431 I GnssLocationProvider: WakeLock acquired by sendMessage(12, 0, null)

05-04 09:11:01.434 5977 5977 D RcsService: Never provisioned and provisioning is not allowed, skipped config update request

05-04 09:11:01.438 13811 13811 I NetworkConnectivity: Network state changed: [type: MOBILE[HSDPA], state: CONNECTED/CONNECTED, reason: connected, extra: iijmio.jp, failover: false, available: true, roaming: false, metered: true]

05-04 09:11:01.451 18316 18316 V BugleThrottledAction: SelfParticipantsRefreshAction scheduled to run now.

05-04 09:11:01.465 3863 3863 I Telephony: PstnIncomingCallNotifier: Unregistering: Handler (com.android.internal.telephony.GsmCdmaPhone) {4be86a2}

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: GPS configuration:

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: #Thu May 04 09:11:01 GMT+09:00 2017

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: NTP_SERVER=north-america.pool.ntp.org

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: INTERMEDIATE_POS=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: A_GLONASS_POS_PROTOCOL_SELECT=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: USE_EMERGENCY_PDN_FOR_EMERGENCY_SUPL=1

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: DEBUG_LEVEL=3

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SUPL_VER=0x20000

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: NMEA_PROVIDER=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SGLTE_TARGET=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: CAPABILITIES=0x37

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: ERR_ESTIMATE=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: XTRA_VERSION_CHECK=1

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SUPL_PORT=7275

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: LPP_PROFILE=0

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: XTRA_SERVER_3=https\://xtrapath3.izatcloud.net/xtra3grc.bin

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SUPL_MODE=1

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: XTRA_SERVER_2=https\://xtrapath2.izatcloud.net/xtra3grc.bin

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: XTRA_SERVER_1=https\://xtrapath1.izatcloud.net/xtra3grc.bin

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SUPL_HOST=supl.google.com

05-04 09:11:01.476 1431 1443 D GnssLocationProvider: SUPL_ES=0

05-04 09:11:01.476 1431 1443 I GnssLocationProvider: WakeLock released by handleMessage(12, 0, null)

05-04 09:11:01.479 1431 3814 E LocSvc_ApiV02: E/virtual enum loc_api_adapter_err LocApiV02::setServer(const char *, int):1027]: error status = eLOC_CLIENT_SUCCESS, set_server_ind.status = eQMI_LOC_ENGINE_BUSY_V02

05-04 09:11:01.485 14517 14517 D CellBroadcastReceiver: onReceive Intent { act=android.intent.action.SERVICE_STATE flg=0x10 cmp=com.android.cellbroadcastreceiver/.CellBroadcastReceiver (has extras) }

05-04 09:11:01.485 14517 14517 D CellBroadcastReceiver: Intent: android.intent.action.SERVICE_STATE

05-04 09:11:01.486 14517 14517 D CellBroadcastReceiver: Service state changed! 1 Full: 1 0 voice home data home null null null null null null Unknown HSDPA CSS not supported -1 -1 RoamInd=-1 DefRoamInd=-1 EmergOnly=false IsDataRoamingFromRegistration=false IsUsingCarrierAggregation=false Current state=0