Microsoft is working to fix CPU throttling on the company’s latest Surface devices, while owners complain of Wi-Fi issues, too. “We are aware of some customers reporting a scenario with their Surface Books where CPU speeds are slowed,” a Microsoft spokesperson said in a statement to TechRepublic. “We are quickly working to address via a firmware update.”

The CPU throttling appears to be affecting both the Surface Book 2 and Surface Pro 6, according to a variety of complaints on Reddit. Processors are getting throttled all the way down to a measly 400MHz, and it’s not immediately clear what is causing the problems. TechRepublic reports that the throttling appears to be related to an Intel CPU flag being locked on by mistake, causing the CPU to throttle as it thinks it’s at a thermal limit.

Alongside the CPU issues, Microsoft’s latest firmware updates have been causing Wi-Fi issues for some. Surface Book and Surface Pro 6 owners have complained on Microsoft’s support forums that the latest Marvel Wi-Fi driver, supplied with Microsoft’s Surface firmware updates on August 1st, is not allowing devices to connect to some 5GHz wireless networks. We experienced these issues on a Surface Pro 6 device, and the problems could be related to certain router combinations.

If you have Wi-Fi issues on a Surface device since the updates earlier this month, you can simply roll back the driver in device manager, which will restore access to 5GHz networks. A Microsoft volunteer moderator claims the company is “working on an update.” We’ve reached out for comment on the Wi-Fi problems.

The latest problems come just weeks after Microsoft halted the rollout of its Windows 10 May 2019 Update to its Surface Book 2 devices. Owners reported issues with the Nvidia GPU disconnecting, and Microsoft is now working on a fix before it makes the update available again. Microsoft’s Surface devices have been largely reliable in recent years, following widespread problems with the original Surface Book and Surface Pro 4 in 2016. The issues led to Consumer Reports removing its “recommended” badge for all Surface hardware, before reinstating it a year later.