EM7355/Skylight (Airwatcher): Device Safety Mode - Temp


Since May of 2017, we’ve deployed around 145 of the Fujitsu Stylistic Q616. All of them use cellular data, overwhelmingly via ATT and we use skylight (airwatcher) to monitor them. They have various feature versions of Windows 10 (1703 - 1803).

Until a couple weeks ago we’ve had no problem. Then, we had a VZW tablet display the “Device Safety Mode | Temp” status on Skylight. In that instance I replaced the SIM and it seemed to work fine after that. We chalked it up to an error with VZW and moved on.

In the past week I’ve now seen 8 instances of this same problem with ATT Sims. We’ve made no changes to the OS or software installed. When the problem is occurring the network status pop up (from the networking icon in the system tray) displays the cellular status as “cellular 2” (or similar) instead of “AT&T (4G LTE) Connected” (for example).

My solution thus far is to reinstall the Sierra Wireless WWAN drivers offered on the Q616 Support page. It works, but the solution is mostly temporary. Sometimes multiple reboots work at keeping it running for a while. We’re also looking at installing new SIM chips, and so far, a little buggy but that might have something to do with it. But why…? I did see on a Lenovo forum that the “Temp” referred to temperature? That the modules are prone to overheating. But why now, 14 months later, randomly, out of the blue?

We used Dell Latitude netbooks with WWAN/SIMS for 7 years and never had a problem like this.

This is a very disruptive problem which could end up being very costly above and beyond the time spent fixing it. All of our users are remote and some don’t have consistent access to reliable wifi further compounding the issue. Fujitsu is, well… Fujitsu.

Has anyone seen this? What causes it? What is the solution? We can’t be the only ones.


Looked like the deployment crossed a couple of Windows 10 versions from RS2 to RS4. What is the original version your IT department has configured the OS for?

There are some major update for Windows 10 Mobile Broadband from RS2 to RS4 in terms of “Let Windows Manage the connection”. If your IT policy is to allow the Windows Update to use WWAN then there will be a lot of data traffic going through the WWAN interface.

It won’t be a big issue if your data plan is not capped, provided you were under good network coverage. But when in a network fringe area or you were under poor network coverage, excessive data traffic with poor signal strength could stress the module to heat up very quick. Factor in the ambient temperature from CPU/GPU on your tablet in a hot summer, the module could get overheated to exceed its set threshold thus going into “Device Safety Mode” by turning the RF off.

You may want to find more details from your field users and try reproduce the issue to further determine what may have caused this.