Don’t mount the Snuza Pico where the baby is likely to lie on-top of it or huddle up around it. The position for the best connection is in the middle of your baby’s tummy.
Don’t have your phone in your pocket. Rather place it on a non-conductive surface.
Try limit the number of obstacles between the Snuza Pico and phone, especially metal obstacles.
2.4Ghz Wifi could interfere with Snuza Pico’s Bluetooth connection to your smart device. If you are using a 2.4GHz Wifi setup in your house to connect your devices to the internet, then rather try to switch to 5GHz.