1. Any iOS devices which are being used for Sharelink should not be used for phone calls. Some cellular carriers (such as Verizon) do not allow simultaneous voice and data services and will stop the data connection used by Sharelink; other carriers may reduce data throughput when a voice call is active.
2. It is recommended that iOS devices are placed in Do Not Disturb mode while you are joined to a Sharelink connection and streaming to prevent any drops from that device. See Apple's article at this link.
3. The VidiU or TeraLink app must be running in the foreground on the iOS device when joined as part of the Sharelink connection. If you press the home button on the iOS device or open another app, or if the device times out from the Auto-Lock setting or is manually placed on the Lock Screen, the Sharelink connection through that device will stop.