It sounds frustrating with your Nothing Phone 2a on Straight Talk (Verizon SIM). Losing data after an initial connection or update, despite seeing VoLTE, is a common issue when a phone isn’t officially supported by Verizon. Locked APN settings on the NP2a definitely doesn’t help.
Verizon doesn’t fully support Nothing Phones, and T-Mobile is usually a better bet in the US due to band compatibility. While some users (myself included with a different Nothing Phone on mainline Verizon) have had luck activating a SIM in a Verizon-approved phone first and then moving it, your experience shows this isn’t foolproof, especially with MVNOs and the NP2a’s specific behavior.
The limited US bands on the NP2a and the network issues you’re seeing after it “syncs” suggest a fundamental incompatibility with Verizon’s network for consistent data. Unfortunately, without editable APNs or official support, it might be tough to get it working reliably on that SIM. As noted, I’m currently on Verizon without issue using a physical SIM I activated previously on another device that Verizon fully supports. Will continue providing community updates if this were to change, but so far so good!
