I have 2 oneplus 6ts and run into this occasionally if the phone is ever restarted. Usually it works fine after flashing an image, but as soon as the phone is restarted, wifi will not function. You can turn it on, and then it will turn itself off. This occasionally leads to freezes in the system UI as well.
The following is logs from after I turn on wifi in the pull-down interface
logcat | grep wifi
11-10 08:49:46.931 1243 9105 I WifiService: setWifiEnabled package=com.android.systemui uid=10215 enable=true isPrivileged=true
11-10 08:49:46.931 1243 1992 D WifiActiveModeWarden: Starting primary ClientModeManager in connect mode
11-10 08:49:46.932 1243 1992 D WifiController: DisabledState.exit()
11-10 08:49:46.932 1243 1992 D WifiController: EnabledState.enter()
11-10 08:49:46.932 1243 1992 D WifiClientModeManager[unknown]: entering IdleState
11-10 08:49:46.935 1243 1992 I android_os_HwBinder: HwBinder: Starting thread pool for getting: android.hardware.wifi@1.0::IWifi/default
11-10 08:49:46.936 1243 1992 I WifiNative: Vendor HAL died. Cleaning up internal state.
11-10 08:49:46.744 0 0 I : Wifi Turning On from UI
11-10 08:50:07.072 1056 1056 E android.hardware.wifi@1.0-service: Wifi HAL start failed
11-10 08:50:07.073 1243 1992 E HalDevMgr: Cannot start IWifi: 9 ()
11-10 08:50:07.073 1243 1992 E WifiVendorHal: Failed to start vendor HAL
11-10 08:50:07.073 1243 1992 E WifiNative: Failed to start vendor HAL
11-10 08:50:07.073 1243 1992 E WifiNative: Failed to start Hal
11-10 08:50:07.074 1243 1992 E WifiClientModeManager[unknown]: Failed to create ClientInterface. Sit in Idle
11-10 08:50:07.074 1243 1992 E WifiActiveModeWarden: ClientModeManager start failed!ConcreteClientModeManager{id=48306501 iface=null role=null}
11-10 08:50:07.074 1243 1992 D WifiScanRequestProxy: Sending scan available broadcast: false
11-10 08:50:07.074 1243 2003 I WifiScanningService: Received a request to disable scanning, UID = 1000
11-10 08:50:07.075 1243 1992 I WifiScanRequestProxy: Scanning is disabled
11-10 08:50:07.075 1243 1992 I WifiCountryCode: No active mode, call onDriverCountryCodeChanged with Null
11-10 08:50:07.075 1243 1992 E WifiActiveModeWarden: One of the native daemons died. Triggering recovery
11-10 08:50:07.075 1243 2003 I WifiScanningService: wifi driver unloaded
11-10 08:50:07.076 1243 1992 E WifiSelfRecovery: Triggering recovery for reason: WifiNative Failure
11-10 08:50:07.076 1243 1992 E WifiSelfRecovery: Already restarted wifi 2 times in last 1 hour. Disabling wifi
11-10 08:50:07.076 1243 1992 E HalDevMgr: IWifiEventCallback.onFailure: 9 ()
11-10 08:50:07.076 1243 1992 I WifiNative: Vendor HAL died. Cleaning up internal state.
11-10 08:50:07.076 1243 1992 D WifiController: STA disabled, return to DisabledState.
11-10 08:50:07.076 1243 1992 D WifiController: EnabledState.exit()
11-10 08:50:07.076 1243 1992 D WifiController: DisabledState.enter()
11-10 08:50:07.076 1243 1992 D WifiController: Recovery has been throttled, disable wifi
11-10 08:50:07.076 1243 1992 D WifiActiveModeWarden: Shutting down all mode managers
11-10 08:50:07.076 1243 1992 E WifiActiveModeWarden: One of the native daemons died. Triggering recovery
11-10 08:50:07.077 1243 1992 E WifiSelfRecovery: Triggering recovery for reason: WifiNative Failure
11-10 08:50:07.077 1243 1992 E WifiSelfRecovery: Already restarted wifi 2 times in last 1 hour. Disabling wifi
11-10 08:50:07.077 1243 1992 D WifiController: Recovery has been throttled, disable wifi
11-10 08:50:07.077 1243 1992 D WifiActiveModeWarden: Shutting down all mode managers
11-10 08:50:07.299 1243 1993 W WifiDiags: could not flush ringbuffer
11-10 08:50:07.358 1243 1992 D WifiNetworkFactory: got request NetworkRequest [ REQUEST id=340, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VCN_MANAGED Uid: 1000 RequestorUid: 10215 RequestorPkg: com.android.systemui UnderlyingNetworks: Null] ]
11-10 08:50:07.358 1243 1992 D UntrustedWifiNetworkFactory: got request NetworkRequest [ REQUEST id=340, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VCN_MANAGED Uid: 1000 RequestorUid: 10215 RequestorPkg: com.android.systemui UnderlyingNetworks: Null] ]
11-10 08:50:07.358 1243 1992 D OemPaidWifiNetworkFactory: got request NetworkRequest [ REQUEST id=340, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VCN_MANAGED Uid: 1000 RequestorUid: 10215 RequestorPkg: com.android.systemui UnderlyingNetworks: Null] ]
11-10 08:50:07.360 1243 1992 D MultiInternetWifiNetworkFactory: got request NetworkRequest [ REQUEST id=340, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED&NOT_VCN_MANAGED Uid: 1000 RequestorUid: 10215 RequestorPkg: com.android.systemui UnderlyingNetworks: Null] ]
11-10 08:50:07.524 1243 1993 W WifiDiags: could not flush ringbuffer
Any idea on a fix? This has persisted across multiple versions, requiring a re-flash of the firmware to fix every time.