For the past month I've had an incredibly annoying problem with my OnePlus 8t (T-Mobile). If my screen is off for a certain amount of time the phone disconnects from the cellular network. Received calls go straight to voicemail. Texts do not arrive. Even when I turn my phone back on I'm not connected to cellular/data. The phone will show I have bars, but no LTE/5G. I have to switch airplane mode on/off to reconnect. I've looked all over and can't find a solution. Any ideas?