Apple’s latest iPhone supports 5G networks, but not if you use the device in dual SIM mode, according to an internal Apple training document revealing the issue that began circulating on Reddit over the weekend.

Dual SIM mode is a feature introduced on the iPhone line with the iPhone XS, and it’s useful for those traveling or staying abroad (or people who maintain work and personal lines on the same device) by allowing both a physical Nano SIM line and data-only service from another carrier using an eSIM simultaneously.

But that apparently interferes with the iPhone 12’s ability to run on 5G networks, at least for now. Here’s the wording from the Apple document:

“Does 5G work with Dual SIM?”

When using two lines in Dual SIM mode, 5G data isn’t supported on either line and will fall back to 4G LTE. If customers are using eSIM only and are on a 5G supported carrier and service plan, they’ll have 5G access.

Apple is reportedly planning an update to fix the issue later this year, according to MacRumors, which cites an internal Verizon slide detailing the company’s 5G support for the iPhone. For now, you can access 5G networks on the iPhone 12 with either a Nano SIM line or an eSIM, so long as you use only a single line at one time, meaning a