Residual NVRAM settings. Fix: Perform a factory reset via the pinhole button on the back of the modem for 30 seconds. This clears old configuration tables.
series. It serves as the low-level software that manages the device's cellular connectivity, acting as the bridge between your phone's hardware and the mobile network. The Apple Wiki The Role of 2.70.01 modem firmware 2.70.01
While changelogs vary by manufacturer, updates in the 2.70.xx branch (specifically the .01 patch) universally target three core pillars of networking. Residual NVRAM settings