The Israeli tech website Calcalist said it had seen internal Intel communications about the issue and also spoken to people said to be familiar with the matter.
It said further development of the modem, known internally as "Sunny Peak" had been halted and the staff involved would be directed to other efforts. The device, a 5G, Wi-Fi and Bluetooth product, was specifically designed for Apple's future smartphones and other mobile devices.
The Intel communications seen by Calcalist described Apple as the "key mobile customer" for the 5G mobile modem and it expected Apple to be the "main volume driver” for the product.
Using a new Wi-Fi standard known as WiGig (802.11ad) in "any mobile product brings new and unanticipated challenges", the communications said.
Intel told the site that it did not comment on matters that concerned its customers.