Hi Sean,
I’ve looked into it with our devs. In some rare cases, the receiver’s hotspot connection may become unstable when there’s a SIM card inside. For now, the reasons are not fully clear, but we continue the investigation. Still, such behavior is hard to reproduce, so the research takes time. Once there are any updates, I’ll let you know.
For now, we can suggest connecting to Reach via Bluetooth as described in this thread. The Bluetooth connection is in Beta, but it may help work with a SIM card in your situation.
If it doesn’t work for you, you can also use the NTRIP over Bluetooth option or connect Reach to a mobile hotspot or a Wi-Fi network.