You have the following options to solve this:
1. Install a LoRa gateway, see: Which LoRa gateways are suitable for the BEEP base?
2. Place a metal plate under the BEEP base, a user of the BEEP base said that this improved the LoRa connection.
3. Connect another LoRa antenna to the BEEP base, see: Replace sensors.
NB: we do not have a lot of experience with other LoRa antennas, so if you find a good one we invite you to share your findings with us so we can pass this on to other users.